Fix get relative locale

[mtwilliams-code]

Changes

fixes #13035
getLocaleRelativeUrl will now return a '/' instead of an empty string in the case of base: '/' and trailingSlash: 'never'.
Changing this behavior of getLocalRelativeUrl caused a similar error in getLocaleAbsoluteUrl for trailingSlash: 'never' because it internaly uses getLocaleRelativeUrl. This is resolved similarly.

Testing

Added tests for both cases - the logic for testing base: '/' had only been testing when trailingSlash:'always'.

Docs

[changeset-bot]

⚠️ No Changeset found

Latest commit: 7c5b4ac

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[codspeed-hq]

CodSpeed Performance Report

Merging #13045 will not alter performance

_{Comparing mtwilliams-code:fix-get-relative-locale (7c5b4ac) with main (f576519)}

Summary

✅ 6 untouched benchmarks

[mtwilliams-code]

oops gotta add the changeset

[ematipico]

Happy to merge once the changeset is ready :)