feat: add query stripping for self telemetry

[goshander]

• Adds the opt-in appTelemetryChSelfStatsStripQueryParams flag.
• Keeps the existing requestUrl behavior by default.
• Prevents large query strings from being sent to telemetry.
• See OpenTelemetry HTTP metrics semantic conventions.

[resure]

Thanks, the change itself looks good and the default-mode test now covering the query string is a nice touch.

One suggestion on the config shape. Right now the switch has two values and one of them means "do nothing", so it is effectively a boolean. A flag would be simpler and would match the neighbouring appTelemetryChEnableSelfStats:

appTelemetryChSelfStatsStripQueryParams?: boolean;

That also removes the StatsUrlMode public export, the README import, and the template-literal type.

If you are planning a third mode later (for example route using req.route.path, which is what the OTel HTTP metrics conventions actually recommend for low cardinality), then keeping an enum makes sense. In that case I would give it a more specific name than StatsUrlMode, e.g. SelfStatsRequestUrlMode, since it is exported at package level.

Two nits:

• README: "stores the original request URL" -> "sends", expresskit does not store anything.
• A short comment above the ternary noting that path mode intentionally skips redactSensitiveQueryParams (nothing left to redact) would prevent someone "fixing" it later.

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🤖 partly ai generated

[goshander]

Thanks, the change itself looks good and the default-mode test now covering the query string is a nice touch.

Replaced the enum with the appTelemetryChSelfStatsStripQueryParams boolean flag, removed the public export
Updated the README, and added a comment explaining why redaction is skipped after stripping the query string.