release-21.2: sql,server: add VIEWACTIVITYREDACTED role

[maryliag]

Backport 1/1 commits from #74715.

/cc @cockroachdb/release

---

This commit adds the new VIEWACTIVITYREDACTED role. This role
should act the same as VIEWACTIVITY for the majority of uses,
but it restricts the usage of Statements Diagnostics Bundle, which
contains PII information.
It is possible for a user to have both VIEWACTIVITY and
VIEWACTIVITYREDACTED, but in this case the VIEWACTIVITYREDACTED
takes precedent and the user can't use the features restricted by it.

Fixes #74716

Release note (sql change): Creation of the new role VIEWACTIVITYREDACTED
that works similar as VIEWACTIVITY but restricts the usage of
Statements Diagnostics Bundle. It is possible for a user to have both roles
(VIEWACTIVITY and VIEWACTIVITYREDACTED), but the role VIEWACTIVITYREDACTED
takes precedent on restrictions.

Release justification: Category 4

[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