release-23.1: workload: remove initial prefix from bank workload payload

[blathers-crl]

Backport 1/1 commits from #102907 on behalf of @renatolabs.

/cc @cockroachdb/release

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An initial- prefix is added to the payload column of the bank table when the workload is initialized. It was introduced about 6 years ago [1] and its purpose at the time is not clear. There are two main problems with it:

• the initial- prefix suggests the payload may be updated, but that actually never happens.
• as currently implemented, it assumes that the payload-bytes command line flag is at least len([]byte("initial-")). Passing a lower value to that command line flag leads to a panic. This is an implicit assumption that should not exist.

This changes the row generation function so that payload-bytes bytes are randomly generated and inserted into the payload column, without the initial- prefix.

[1] d49d535

Epic: none

Release note: None

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Release justification:

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• 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 

[renatolabs]

On second thought, now that 23.1.0 is picked, it doesn't make that much sense to backport this. We'll just have to live with the initial- prefix for a while. Closing.