sql, storage: tolerate existing splits in AdminSplit and SPLIT AT

[RaduBerinde]

This error is not useful; indeed many callers go through hoops to ignore it.
Extending SPLIT AT to handle multiple split points makes this error even more
annoying. Removing this error in favor of a silent no-op (based on discussion
in #14146).

The backup test is changed to read the meta descriptor instead on relying on
the old behavior to verify splits.

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This change is 

[tamird]

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Reviewed 8 of 8 files at r1.
Review status: all files reviewed at latest revision, 2 unresolved discussions, all commit checks successful.

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pkg/kv/split_test.go, line 231 at r1 (raw file):

	splitKey := roachpb.Key("aa")
	log.Infof(context.Background(), "starting split at key %q...", splitKey)

yikes, this mixing of contexts. while you extract one while you're here?

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pkg/storage/client_split_test.go, line 317 at r1 (raw file):

		if pErr != nil {
			// There are only two expected errors from concurrent splits:
			// conflicting range descriptors if the splits are initiated

huh, how come the conflicting descriptor case is absent?

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Comments from Reviewable

[RaduBerinde]

pkg/storage/client_split_test.go, line 317 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

huh, how come the conflicting descriptor case is absent?

Sorry, I'm confused by the question. I just removed the "range already split" error case since that's no longer a thing.

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Comments from Reviewable

[RaduBerinde]

pkg/storage/client_split_test.go, line 317 at r1 (raw file):

Previously, RaduBerinde wrote…

Sorry, I'm confused by the question. I just removed the "range already split" error case since that's no longer a thing.

Ah, absent from the list of expected errors? No idea, I'll try to hunt down whoever touched this code.

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Comments from Reviewable

[RaduBerinde]

pkg/storage/client_split_test.go, line 317 at r1 (raw file):

Previously, RaduBerinde wrote…

Ah, absent from the list of expected errors? No idea, I'll try to hunt down whoever touched this code.

Looks like it was removed in 4b0578a @vivekmenezes do we need to update this comment?

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Comments from Reviewable

[tamird]

Review status: all files reviewed at latest revision, 2 unresolved discussions, all commit checks successful.

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pkg/kv/split_test.go, line 231 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

yikes, this mixing of contexts. while you extract one while you're here?

that should be "can you ...". not sure how i mangled that sentence so badly.

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pkg/storage/client_split_test.go, line 317 at r1 (raw file):

Previously, RaduBerinde wrote…

Looks like it was removed in 4b0578a @vivekmenezes do we need to update this comment?

Yeah, looks like you can update the comment and remove the strings.Join dance. Thanks for tracking it down.

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Comments from Reviewable

[RaduBerinde]

TFTR!

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Review status: all files reviewed at latest revision, 2 unresolved discussions, all commit checks successful.

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pkg/kv/split_test.go, line 231 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

that should be "can you ...". not sure how i mangled that sentence so badly.

Done. Did it for the entire file (in a separate commit).

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pkg/storage/client_split_test.go, line 317 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

Yeah, looks like you can update the comment and remove the strings.Join dance. Thanks for tracking it down.

Done.

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Comments from Reviewable

[tamird]

Reviewed 1 of 8 files at r1, 1 of 1 files at r2, 1 of 1 files at r3.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks pending.

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Comments from Reviewable

[maddyblue]

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Review status: all files reviewed at latest revision, all discussions resolved, all commit checks successful.

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Comments from Reviewable