Add Twenty Twenty-Five to the Performance Tests

[joemcgill]

During the release party for WP 6.7-beta1, it was discovered that adding Twenty Twenty-Five to the Performance Tests caused an error when tested in the baseline version of WordPress, which that theme does not currently support. To address those failures, the theme was removed from the performance tests in [59151].

We should start collecting performance data for this new default theme, so we either need to update the baseline used conditionally based on the theme we're testing, or consider updating the baseline for all performance tests.

[SergeyBiryukov]

Looking into the ​performance tests failure for TT5:

Fatal error: Uncaught Error: Call to undefined function register_block_bindings_source() in /var/www/build/wp-content/themes/twentytwentyfive/functions.php:131

It appears that the baseline version for performance tests is WP 6.1.1, whereas register_block_bindings_source() was added in [57375] / #60282 for WP 6.5.

The 6.1.1 baseline version was added in [55459] / #57687, back when trunk was 6.2. Should it be updated to 6.6.2 now?

[joemcgill]

After discussion in the #core-performance bug scrub earlier today, we determined to push this to 6.8-early, since making any changes to the workflow that will impact the baselines would be risky until after the release. Even then, it will be important to keep in mind that all release branches use a reusable workflow from trunk, so changes after branching could still affect the 6.7 release.