storage: fix quiescence when not leaseholder

[petermattis]

Fix check for whether we own a valid lease.

Fixes #17741

[cockroach-teamcity]

This change is 

[bdarnell]

We should go ahead and merge this (and assuming it fixes the problem, patch it in for the beta), but we need a follow-up issue to add more testing for quiescence and specifically a test that would be sensitive to this issue.

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Comments from Reviewable

[petermattis]

Merging and filing an issue to test this area of quiescence. I won't be able to cherry-pick into the release branch until later tonight (after 8pm).

[bdarnell]

OK, I'll do the cherry-pick in #18184

[bdarnell]

adriatic had been in the zero qps state and recovered when this change was deployed (not conclusive since it doesn't always get stuck, but a good sign). omega and cerulean were fine before this change was deployed and fine after. omega appeared to suffer more disruption to traffic during the push than usual.

[petermattis]

@bdarnell adriatic and omega are both running 8633ca4 which does not have your cherry-pick (3cab35b).

[bdarnell]

adriatic and omega are both running 8633ca4 which does have your cherry-pick (3cab35b).

That's what I mean. I was describing the push of 8633ca4 to the test clusters.