Cancel PG query if stuck at refreshing configuration (#12717)

## Problem

While configuring or reconfiguring PG due to PageServer movements, it's
possible PG may get stuck if PageServer is moved around after fetching
the spec from StorageController.

## Summary of changes

To fix this issue, this PR introduces two changes:
1. Fail the PG query directly if the query cannot request configuration
for certain number of times.
2. Introduce a new state `RefreshConfiguration` in compute tools to
differentiate it from `RefreshConfigurationPending`. If compute tool is
already in `RefreshConfiguration` state, then it will not accept new
request configuration requests.

## How is this tested?
Chaos testing.

Co-authored-by: Chen Luo <chen.luo@databricks.com>

control_plane/src/endpoint.rs

@@ -938,7 +938,8 @@ impl Endpoint {
                         | ComputeStatus::TerminationPendingFast
                         | ComputeStatus::TerminationPendingImmediate
                         | ComputeStatus::Terminated
-                        | ComputeStatus::RefreshConfigurationPending => {
+                        | ComputeStatus::RefreshConfigurationPending
+                        | ComputeStatus::RefreshConfiguration => {
                             bail!("unexpected compute status: {:?}", state.status)
                         }
                     }