docs: PHPStan Cache no type specified

[ddevsr]

Description
See #7731

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[kenjis]

Please rebase to resolve conflict.

[paulbalandan]

I see 8 deletes in baseline but only 2 files are changed (CacheInterface and MockCache). It seems the change in CacheInterface affects the handlers but why is MockCache still annotated?

[kenjis]

Thank you!