catalog/lease: deflake TestLeaseManagerLockedTimestampCluster

[fqazi]

The test was flaking because it used TestingDescriptorUpdateEvent, which fires before a new version of a descriptor is accquired. To address this, we switch to TestingDescriptorRefreshedEvent, which fires when a new version of a descriptor is acquired. This helps the test become less flakey, because we guarantee that new versions are fully acquired before getting blocked on a channel. Additionally, one of the assertDescriptorCount was in a place where a older timestamp could be acquired, so the assertion itself was race condition prone.

Fixes #165857
Fixes: #166081

Release note: None

[trunk-io]

😎 Merged successfully - details.

[cockroach-teamcity]

This change is 

[rafiss]

nice fix!

@rafiss made 6 comments.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on fqazi).

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-- commits line 2 at r1:
nit: ctalog

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-- commits line 5 at r1:
nit: accquired -> acquired

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pkg/sql/catalog/lease/lease_internal_test.go line 1976 at r1 (raw file):

		require.NotNil(t, newest)
		lastVersion := newest.GetVersion()
		t.Helper()

nit: t.Helper should be the first line of the function. though in this case, i don't think we should use t.Helper at all; it will hide which line failed.

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pkg/sql/catalog/lease/lease_internal_test.go line 1982 at r1 (raw file):

		<-newVersionCh
		newest, _ = lm.findNewest(descpb.ID(id))
		// Ensure that the new version is accuired. To avoid any race

nit: accuired -> acquired

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pkg/sql/catalog/lease/lease_internal_test.go line 1991 at r1 (raw file):

		releaseNextVersion = true
	}
	// Initial state we only expect a single version.

nit: use a sentence; "In the initial state we only expect a single version."

[fqazi]

@fqazi resolved 5 discussions.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on rafiss).

[fqazi]

@rafiss TFTR

/trunk merge

[blathers-crl]

Based on the specified backports for this PR, I applied new labels to the following linked issue(s). Please adjust the labels as needed to match the branches actually affected by the issue(s), including adding any known older branches.

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Issue #166081: branch-release-26.2.

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Issue #165857: branch-release-26.1, branch-release-26.2.

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