release-21.2: sql,jobs: implement redact.SafeValue for JobID and SessionID

[stevendanna]

Backport 1/1 commits from #71062.

/cc @cockroachdb/release

---

jobspb.JobID is an int64, populated via unique_rowid() at the
point of job creation.

sqlliveness.SessionID is a string but represents an opaque
identifier. In the current implementation, it is the bytes from a V4
UUID.

jobspb.JobIDs currently appear in many log messages and are fairly
valuable when trying to track what happened to a particular job. For
example,

Before:

[n1] 60 CHANGEFEED job ‹×›: stepping through state running with error: <nil>

After:

[n1] 81 CHANGEFEED job 698867169229307905: stepping through state running with error: <nil>

SessionID's are not logged in many places currently, but I would like
to include them in error messages in the near future.

Release note (ops change): Job IDs and Session IDs are no longer
redacted. These values do not represent sensitive or identifiable
data, but do aid in debugging problems with the jobs system.

Release justification: Low risk change to improve jobs debugability.

[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