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>

libs/compute_api/src/responses.rs

@@ -174,6 +174,9 @@ pub enum ComputeStatus {
     Terminated,
     // A spec refresh is being requested
     RefreshConfigurationPending,
+    // A spec refresh is being applied. We cannot refresh configuration again until the current
+    // refresh is done, i.e., signal_refresh_configuration() will return 500 error.
+    RefreshConfiguration,
 }
 
 #[derive(Deserialize, Serialize)]
@@ -186,6 +189,10 @@ impl Display for ComputeStatus {
         match self {
             ComputeStatus::Empty => f.write_str("empty"),
             ComputeStatus::ConfigurationPending => f.write_str("configuration-pending"),
+            ComputeStatus::RefreshConfiguration => f.write_str("refresh-configuration"),
+            ComputeStatus::RefreshConfigurationPending => {
+                f.write_str("refresh-configuration-pending")
+            }
             ComputeStatus::Init => f.write_str("init"),
             ComputeStatus::Running => f.write_str("running"),
             ComputeStatus::Configuration => f.write_str("configuration"),
@@ -195,9 +202,6 @@ impl Display for ComputeStatus {
                 f.write_str("termination-pending-immediate")
             }
             ComputeStatus::Terminated => f.write_str("terminated"),
-            ComputeStatus::RefreshConfigurationPending => {
-                f.write_str("refresh-configuration-pending")
-            }
         }
     }
 }