release-21.2: roachtest: fix multitenant-upgrade

[blathers-crl]

Backport 1/1 commits from #71604 on behalf of @tbg.

Fixes #71269.

/cc @cockroachdb/release

---

In #71040 we added disk spilling for tenants which added the following
call to the mt start-sql code path:

https://github.com/cockroachdb/cockroach/blob/af5a5a5065ce80c5e6568b4b422bf5c3a179e173/pkg/cli/mt_start_sql.go#L90-L89

The defaults for the store match that of a regular CockroachDB node, and
the tenant will thus attempt to clean up temp dirs for cockroach-data
if no store is specified:

cockroach/pkg/cli/start.go

Lines 223 to 227 in 6999e5f

	recordPath := filepath.Join(spec.Path, server.TempDirsRecordFilename)
	if err := storage.CleanupTempDirs(recordPath); err != nil {
	return base.TempStorageConfig{}, errors.Wrap(err,
	"could not cleanup temporary directories from record file")
	}

In the multitenant-upgrade roachtest, as it happens there was actually
a cockroach host instance running under cockroach-data, and so the
tenant would fail to try to remove its (locked) temp dirs.

Fix that by passing the --store flag to the tenants in this test. This
is mildly annoying since the predecessor version doesn't understand it
and so the test has to figure out when it is legal to pass it. Anyway,
it is done now.

I will point out that it isn't the greatest choice to have tenants
default to cockroach-data as the resulting interaction with a CRDB
server results in an unfortunate UX. I filed #71603 to that effect.

Closes #69920

Release note: None

---

Release justification:

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[cockroach-teamcity]

This change is 

[jaylim-crl]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @tbg)

[tbg]

Not sure what the rules for merging are these days, but going to keep this open until we've released.

[tbg]

Hmm actually merging this would give us coverage of the upgrade process, so I should ask to merge this.

[tbg]

Got approval from Isaac.