[12.x] Improve Cache Tests

[nuernbergerA]

Hey,

inspired from today' s stream by @jasonmccreary (about atomic locks and the struggle to test the exception)
i've added a missing test which also can be used as an example on how to test lock/block for other users.

• Each test had Cache::lock('foo')->forceRelease(); as first line => moved to setUp
• found a slow test using sleep(2) to test the lock is release afterwards => used Sleep facade which is use in Cache
• added a missing test for the exception when block runs into a timeout

let me know if i should split this up into more PRs.

cheers
adrian

[jasonmccreary]

Nice follow-up @nuernbergerA!