server: initialize DBContext with correct instance ID

[stevendanna]

Before this change the DBContext in a tenant would always have a zero'd SQLInstanceID.

Note that for SQL pods not co-located on an KV-node, OptionalNodeID() should still return 0 and anything that requires a NodeID rather than an InstanceID should be using that method.

Informs: #96353

Epic: none

Release note: None

[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is 

[knz]

wow nice catch

[stevendanna]

bors r=knz

[j82w]

-- commits line 11 at r1:
This fixes: #96353

[j82w]

pkg/server/tenant.go line 1022 at r1 (raw file):

	dbCtx := kv.DefaultDBContext(stopper)
	dbCtx.NodeID = instanceIDContainer
	db := kv.NewDBWithContext(baseCfg.AmbientCtx, tcsFactory, clock, dbCtx)

Is it possible to add an assert or test to prevent future regressions?

[stevendanna]

bors cancel

[craig]

Canceled.

[stevendanna]

@j82w Good call. I'll see what happens if I add a few assertion failures in places where we expect to have a sql instance ID.

[stevendanna]

bors r=knz

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)