tests: adopt synctest in some places

[npazosmendez]

What this PR does

A bunch of tests that play with sleeps, tickers, etc. can be sped up greatly by simply wrapping them with synctest.Test. There are still a bunch of other tests that would benefit from this, but I tried to scope it down to the ones that just needed to be wrapped, to start with.

Review with "Hide whitespace" for saneness

Speed up breakdown

Ran locally. This will not have the same impact on CI, mostly because tests are parallelized.

Test	main	this PR
TestMultiDimensionalQueueAlgorithmSlowConsumerEffects	10.49s	0.11s
TestRemoteQuerier_QueryRetryOnFailure	8.00s	0.00s
TestRecordAndReportRuleQueryMetrics	6.00s	0.00s
TestStoreGateway_InitialSyncFailure	5.15s	0.00s
TestRulerSyncQueue_ShouldNotNotifyChannelMoreFrequentlyThanPollFrequency	5.00s	0.00s
TestRemoteQuerier_StatusErrorResponses	4.00s	0.00s
TestLifecycler_CheckReady	2.39s	0.00s
TestReaderPool_ShouldCloseIdleLazyReaders	2.14s	0.13s
TestRuler_NotifySyncRulesAsync_ShouldNotTriggerRulesSyncingOnAllRulersWhenDisabled	1.46s	0.01s
TestHATrackerCheckReplicaShouldFixZeroElectedAtTimestamp	1.11s	0.00s
TestIngesterRestart	0.90s	0.00s
TestAwaitQueryFrontendServiceRunning_ServiceIsNotReadyInitially	0.50s	0.00s
Total	47.1s	0.25s

Which issue(s) this PR fixes or relates to

n/a

Checklist

• [n/a] Tests updated.
• [n/a] Documentation added.
• [n/a] CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]. If changelog entry is not needed, please add the changelog-not-needed label to the PR.
• [n/a] about-versioning.md updated with experimental features.

[pitasi]

please rebase this PR on latest main, otherwise it can't merge — it's blocked on required checks that will never report.

context: #16335 changed the unit test CI matrix and the required checks got renamed (test (N, 10) → test (N, 5)). CI runs from before that change only report the old names, so the branch needs to pick up the new workflow from main. sorry for the churn.

[narqo]

Structurally, the changes make sense 🔥

I think, in the future we can improve individual tests, which may not even need time.Sleep under the synctest. Thank you for working on that