kvprober reports errors on a decommissioned node

[joshimhoff]

Describe the problem

Today, kvprober runs on a decommissioned node. In CC, this is generally fine, since automation fully takes down nodes once they reach the decommissioned state. But there is a brief period where a node is running and in the decommissioned state, and we saw kvprober errors during this period. This sometimes leads to kvprober errors like what is below:

‹rpc error: code = PermissionDenied desc = n1 was permanently removed from...

To be clear, the errors are not wrong. They just are expected to happen, once a node is decommissioned. Tho they are not wrong per say, we will call them a bug, since they can lead to alerting false positive.

To Reproduce

See test at #104365.

Behavior we want

No errors when a node enters the decommissioned state.

Jira issue: CRDB-28490