release-21.2: ui: range table loads correctly when replica is being gc-ed

[blathers-crl]

Backport 1/1 commits from #69443 on behalf of @dhartunian.

/cc @cockroachdb/release

---

Previously, there was a bug where the range table component would fail
to load if the GetLocalReplica function returned a null or undefined
value. This is an expected scenario where we may be in the Awaiting GC
state for a problematic range.

This change gates the retrieval of .type on the localReplica object
on the awaitingGC boolean like a few other cases in the component do
already. We render blank text for the replicaType in this scenario
since the row right above will show "Awaiting GC" already.

Release justification: this is a high-severity bug on the page since it
doesn't load in scenarios where we would want to debug problematic
ranges.

Release note (ui change, bug fix): replicas awaiting to be GCed were
causing the range report page to not load at all due to a JS error. The
page will now load and display an empty "Replica Type" while in this
state.

---

Release justification: this fixes a bug in the DB Console where the range report page would fail to load

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues.
• 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 

[nathanstilwell]

LGTM