release-22.2: roachtest: load AWS fixtures from us-east-2 to avoid egress

[srosenberg]

Backport 1/1 commits from #105969.

/cc @cockroachdb/release

---

In [1], new restore tests have been added to load fixtures from s3://cockroach-fixtures. Since the regional bucket is located in us-east-1, and roachprod provisions in us-east-2, egress during nightly and weekly runs amounted to non-trivial cost.

This change replaces the bucket with the regional
s3://cockroach-fixtures-us-east-2, which was replicated from us-east-1. As a precaution, other roachtest which depend on s3://cockroach-fixtures but do not currently run in AWS, are now guarded by a conditional skip. A new issue (#105968) has been created to address
the problem of localizing fixtures under a given
cloud provider.

[1] #94143

Epic: none
Informs: #105968

Release note: None
Release justification: ci/test only change

[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