test: migrate constants/float64/ln-two-pi to ULP-based assertions

[Planeshifter]

Resolves a task from #11352.

Description

What is the purpose of this pull request?

This pull request:

• migrates the ln(2*pi) assertion in constants/float64/ln-two-pi from an EPS-based tolerance to isAlmostSameValue from @stdlib/assert/is-almost-same-value.
• uses a single named ULP constant of 1, which is the measured minimum that passes (0 ULP fails, since ln( 2.0*PI ) differs from the constant by 1 ULP). The suite was run twice at this value with identical, passing results.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• [RFC]: Migrate math/base/special packages from relative tolerance testing to ULP difference testing (tracking issue) #11352

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Only test/test.js is changed; ESLint passes.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

AI Assistance

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• No

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• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
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Disclosure

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This PR was written primarily by Claude Code (scheduled routine).

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@stdlib-js/reviewers

🤖 Generated with Claude Code

https://claude.ai/code/session_0157PdQFGkHiseLjJiHZNFNP

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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
constants/float64/ln-two-pi	$\\color{green}52/52$ $\\color{green}+0.00\\%$	$\\color{green}1/1$ $\\color{green}+0.00\\%$	$\\color{green}0/0$ $\\color{green}+0.00\\%$	$\\color{green}52/52$ $\\color{green}+0.00\\%$

The above coverage report was generated for the changes in this PR.

[kgryte]

LGTM after clean-up