Remove cache tag checksum assertions from performance tests

> not really a way to deprecate an array key.

Well, the array keys map to methods, so deprecating those should trigger deprecations.

Possibly this is major/critical as it looks like StandardPerformanceTest has a new fairly frequent random fail?

yesterday faced the same working on 📌 Remove UI and routes for the ability to update modules and themes via update.module and authorize.php Active
ref https://git.drupalcode.org/issue/drupal-3502973/-/jobs/4561201
basically it vary

    Standard Performance (Drupal\Tests\standard\FunctionalJavascript\StandardPerformance)
     ✘ Standard performance
       ┐
       ├ Failed asserting that two arrays are identical.
       ┊ ---·Expected
       ┊ +++·Actual
       ┊ @@ @@
       ┊      ],
       ┊      'CacheSetCount' => 45,
       ┊      'CacheDeleteCount' => 0,
       ┊ -····'CacheTagChecksumCount'·=>·38,
       ┊ -····'CacheTagIsValidCount'·=>·43,
       ┊ +····'CacheTagChecksumCount'·=>·37,
       ┊ +····'CacheTagIsValidCount'·=>·42,
       ┊      'CacheTagInvalidationCount' => 0,
       ┊      'CacheTagLookupQueryCount' => 21,
       ┊      'CacheTagGroupedLookups' => Array &2 [
       │
       │ /builds/issue/drupal-3502973/core/tests/Drupal/Tests/PerformanceTestTrait.php:679
       │ /builds/issue/drupal-3502973/core/profiles/standard/tests/src/FunctionalJavascript/StandardPerformanceTest.php:175
       │ /builds/issue/drupal-3502973/core/profiles/standard/tests/src/FunctionalJavascript/StandardPerformanceTest.php:57

Bumping to critical due to the random test failures, I think all the places we're removing the deprecated methods are using the new better ones now.

phpstan needs fixes

Green pipeline now.

Looks good to me.

Checked deprecation messages.

Read through the change record as well.