sql: use seeded random for schemachange opsgen

[annrpom]

A schemachange TestWorkload failure was difficult to reproduce; to address this, this patch uses randutil's NewTestRand() to allow for a global seed to be set when stressing this test.

Epic: none
Informs: #108695
Informs: #105517
Informs: #109218
Release note: none

[cockroach-teamcity]

This change is 

[annrpom]

The failure originated from branch 23.1, but was last seen on 23.1.9-rc - we should backport to the branch that has seen the most recent failure. Not sure if we want to backport to 23.1 as well

[renatolabs]

This is great, I remember wanting this in the past (for reproducing test failures).

If we're changing this code, it might be a good time to also support passing the seed as a command line argument. Lots of workloads already do it so it would be more consistent.

There's some shared code in workload/random.go that we ca use [1]. See the bank workload [2] for an example of it being used.

[1]

cockroach/pkg/workload/random.go

Lines 26 to 28 in 9849680

	type RandomSeed interface {
	LogMessage() string
	}

[2]

cockroach/pkg/workload/bank/bank.go

Line 45 in 9849680

var RandomSeed = workload.NewUint64RandomSeed()

[rafiss]

lgtm, just need to fix the release note!

also, in the PR description can you link to the test that prompted this. add a line like:

informs https://github.com/cockroachdb/cockroach/issues/108695
informs https://github.com/cockroachdb/cockroach/issues/105517

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @annrpom, @herkolategan, and @smg260)

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-- commits line 11 at r1:
nit: this should have Release note: None since this is not a change that end-users need to know about.

[renatolabs]

(Forgot to mention my comment is totally optional; that can be done in the future)

[annrpom]

thank you for the suggestion, @renatolabs i'll keep that in mind :]

[annrpom]

TFTR! ('-')7

bors r+

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

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error creating merge commit from b21b3e5 to blathers/backport-release-23.1-108922: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 23.1.x failed. See errors above.

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error creating merge commit from b21b3e5 to blathers/backport-release-23.1.9-rc-108922: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 23.1.9-rc failed. See errors above.

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