[ci] Build ruby CIPD packages with Xcode 17c52

[okorohelijah]

Both ruby builders have been failing at build package because Homebrew requires Xcode >= 16.0 on macOS 15 and they request Xcode 15a240d:

Error: Your Xcode (15.0 => /opt/flutter/xcode/15a240d/XCode.app/Contents/Developer) at /Applications/Xcode.app is too outdated.
Please update to Xcode 26.3 (or delete it).

Move both to 17c52 (Xcode 26.2), the version every other Flutter builder uses, so mac-amd64 and mac-arm64 are built with the same toolchain. This also keeps them aligned with the Intel Xcode pin in https://flutter-review.googlesource.com/c/recipes/+/83760, which would otherwise change only the amd64 builder.

Examples: https://ci.chromium.org/b/8670377120581308353 (Mac ruby), https://ci.chromium.org/b/8670377021801718401 (Mac_arm64 ruby).

What this does and does not fix

Homebrew's fatal_build_from_source_checks are fatal (exit 1) for brew reinstall --build-from-source, which cipd_packages/ruby/tools/build.sh uses; on Intel Homebrew no longer ships bottles at all, so even brew install curl builds from source. This PR clears one of those checks:

• check_xcode_minimum_version (Xcode >= 16.0 on macOS 15) — fixed here.
• check_if_xcode_needs_clt_installed — /Library/Developer/CommandLineTools is not present on the devicelab hosts (Error: Xcode alone is not sufficient on Sequoia). Host provisioning, not fixable from .ci.yaml. Tracked in Mac ruby failing due to missing command line tools flutter#162344.
• Once ruby compiles, pod --version failed through mid-2025 with uninitialized constant ActiveSupport::LoggerThreadSafeLevel::Logger (cocoapods 1.16.2 + activesupport 7.0.8). Tracked in Mac ruby failing due to ActiveSupport issue flutter#162341. Likely to reappear.

So these builders will stay red after this lands; this is a prerequisite, not the fix. Umbrella: flutter/flutter#164665.

Note on os: "Mac-15.5|Mac-15.7": 17c52 requires macOS 15.6, but there are currently 0 macOS 15.5 bots in luci.flutter.prod (150 Mac bots, all 15.7.x), so the dimension is left as is.

Consumers are unaffected either way: every ruby dependency in flutter/flutter (80) and flutter/packages (1) pins CIPD ref ruby_3.1-pod_1.13 (registered 2023-10-23); these builders only re-register latest.

[gemini-code-assist]

Code Review

This pull request updates the macOS SDK version (sdk_version) for the $flutter/osx_sdk target from 15a240d to 17c52 in the .ci.yaml configuration file. There are no review comments to address, and I have no additional feedback to provide.

[okorohelijah]

Proposal: rather than land this, we could delete both ruby targets (and cipd_packages/ruby) instead.

This PR only clears the first of three blockers (see description). Getting these builders green also needs Command Line Tools on the devicelab image (flutter/flutter#162344) and a CocoaPods/ActiveSupport dependency fix in the build script (flutter/flutter#162341). That's real work across two teams for a package that, as far as I can tell, has no remaining reason to exist:

• CocoaPods is being deprecated. SwiftPM is the default now, and [SwiftPM] Deprecate CocoaPods flutter#168015 tracks dropping CocoaPods support entirely; Remove CocoaPods from integration tests flutter#183649 is already removing it from integration tests. The only purpose of flutter/ruby/* is to ship a Ruby with CocoaPods preinstalled.
• Nobody consumes new builds. All 80 ruby dependencies in flutter/flutter and the 1 in flutter/packages pin ruby_3.1-pod_1.13, an immutable CIPD ref from 2023-10-23. These builders only re-register latest, which nothing uses; they last succeeded ~Jan 2025 (amd64) / ~Sep 2024 (arm64) and no one noticed.
• Intel is Tier 3 in Homebrew (no bottles since 2025-08), so Mac ruby builds everything from source and will only get more fragile; Intel hosts are being retired anyway.

@vashworth wdyt?

[vashworth]

Proposal: rather than land this, we could delete both ruby targets (and cipd_packages/ruby) instead.

This PR only clears the first of three blockers (see description). Getting these builders green also needs Command Line Tools on the devicelab image (flutter/flutter#162344) and a CocoaPods/ActiveSupport dependency fix in the build script (flutter/flutter#162341). That's real work across two teams for a package that, as far as I can tell, has no remaining reason to exist:

• CocoaPods is being deprecated. SwiftPM is the default now, and [SwiftPM] Deprecate CocoaPods flutter#168015 tracks dropping CocoaPods support entirely; Remove CocoaPods from integration tests flutter#183649 is already removing it from integration tests. The only purpose of flutter/ruby/* is to ship a Ruby with CocoaPods preinstalled.
• Nobody consumes new builds. All 80 ruby dependencies in flutter/flutter and the 1 in flutter/packages pin ruby_3.1-pod_1.13, an immutable CIPD ref from 2023-10-23. These builders only re-register latest, which nothing uses; they last succeeded ~Jan 2025 (amd64) / ~Sep 2024 (arm64) and no one noticed.
• Intel is Tier 3 in Homebrew (no bottles since 2025-08), so Mac ruby builds everything from source and will only get more fragile; Intel hosts are being retired anyway.

@vashworth wdyt?

Technically we still use CocoaPods in CI so we may have future use for these builders. Currently, they fail consistently and have for a while (they are in bringup), but I don't want to be blocked by figuring out the ramifications of removing these entirely. Let's file an issue to track removing these and we can follow up when appropriate.