[cuebot] Fix channel closing issue (#2274)

The application os not properly closing the grpc channel at shutdown,
leaving this SEVERE warning:

```
Channel ManagedChannelImpl{logId=2787, target=elk0815:8444} was not shutdown properly
```

Explanation:

`RqdClientGrpc`
(cuebot/src/main/java/com/imageworks/spcue/rqd/RqdClientGrpc.java:71-89)
holds a Guava `LoadingCache<String, ManagedChannel>`. The
`removalListener` calls `conn.shutdown()` **on cache eviction** — but
never on application shutdown. The bean has no `destroy-method`
(applicationContext-service.xml:39, no destroy hook), and
`RqdClientGrpc` has no `shutdown()` method at all. So when cuebot stops:

- The cache is GC'd
- Each `ManagedChannel` is finalized **without** `shutdown()` having
been called
- gRPC logs `SEVERE: Channel ... was not shutdown properly!!!` per
leaked channel, with the stack capturing where the channel was first
allocated (the `RuntimeException: ManagedChannel allocation site` —
that's a diagnostic stack, not a real exception)


## LLM usage disclosure

Claude Opus was used for investigating the origin of the log and
proposing a fix


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Improved application shutdown procedure to properly clean up network
resources and prevent potential resource leaks during shutdown.
* Enhanced shutdown sequencing to ensure proper initialization and
cleanup order of internal services.

[![Review Change
Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/AcademySoftwareFoundation/OpenCue/pull/2274)

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: DiegoTavares

cuebot/src/main/java/com/imageworks/spcue/rqd/RqdClientGrpc.java

@@ -216,4 +216,11 @@ public void launchFrame(final RunFrame frame, final VirtualProc proc) {
     public void setTestMode(boolean testMode) {
         this.testMode = testMode;
     }
+
+    public void shutdown() {
+        if (channelCache != null) {
+            logger.info("Shutting down RqdClientGrpc channel cache");
+            channelCache.invalidateAll();
+        }
+    }
 }

cuebot/src/main/resources/conf/spring/applicationContext-service.xml

@@ -36,7 +36,7 @@
   <!-- Non-Transactional Service Domain -->
   <!-- ##################################################################################### -->
 
-  <bean id="rqdClient" class="com.imageworks.spcue.rqd.RqdClientGrpc">
+  <bean id="rqdClient" class="com.imageworks.spcue.rqd.RqdClientGrpc" destroy-method="shutdown">
     <constructor-arg index="0" type="int">
       <value>${grpc.rqd_server_port}</value>
     </constructor-arg>
@@ -66,7 +66,7 @@
     <property name="queueCapacity" value="500" />
   </bean>
 
-  <bean id="bookingQueue" class="com.imageworks.spcue.dispatcher.BookingQueue" lazy-init="true" destroy-method="shutdown" depends-on="cueDataSource">
+  <bean id="bookingQueue" class="com.imageworks.spcue.dispatcher.BookingQueue" lazy-init="true" destroy-method="shutdown" depends-on="cueDataSource,rqdClient">
     <constructor-arg index="0" type="int">
       <value>${booking_queue.threadpool.health_threshold}</value>
     </constructor-arg>
@@ -85,7 +85,7 @@
     <property name="shutdownDrainMs" value="${healthy_threadpool.shutdown_drain_ms:60000}"/>
   </bean>
 
-  <bean id="dispatchQueue" class="com.imageworks.spcue.dispatcher.DispatchQueue" destroy-method="shutdown" depends-on="cueDataSource">
+  <bean id="dispatchQueue" class="com.imageworks.spcue.dispatcher.DispatchQueue" destroy-method="shutdown" depends-on="cueDataSource,rqdClient">
     <constructor-arg index="0" type="java.lang.String">
       <value>DispatchQueue</value>
     </constructor-arg>
@@ -107,7 +107,7 @@
     <property name="shutdownDrainMs" value="${healthy_threadpool.shutdown_drain_ms:60000}"/>
   </bean>
 
-  <bean id="manageQueue" class="com.imageworks.spcue.dispatcher.DispatchQueue"   destroy-method="shutdown" depends-on="cueDataSource">
+  <bean id="manageQueue" class="com.imageworks.spcue.dispatcher.DispatchQueue"   destroy-method="shutdown" depends-on="cueDataSource,rqdClient">
     <constructor-arg index="0" type="java.lang.String">
       <value>ManageQueue</value>
     </constructor-arg>
@@ -128,7 +128,7 @@
     </constructor-arg>
     <property name="shutdownDrainMs" value="${healthy_threadpool.shutdown_drain_ms:60000}"/>
   </bean>
-  <bean id="reportQueue" class="com.imageworks.spcue.dispatcher.HostReportQueue" destroy-method="shutdown" depends-on="cueDataSource">
+  <bean id="reportQueue" class="com.imageworks.spcue.dispatcher.HostReportQueue" destroy-method="shutdown" depends-on="cueDataSource,rqdClient">
     <constructor-arg index="0" type="int">
       <value>${report_queue.threadPoolSizeInitial}</value>
     </constructor-arg>
@@ -140,7 +140,7 @@
     </constructor-arg>
     <property name="shutdownDrainMs" value="${host_report_queue.shutdown_drain_ms:60000}"/>
   </bean>
-  <bean id="killQueue" class="com.imageworks.spcue.dispatcher.HostReportQueue" destroy-method="shutdown" depends-on="cueDataSource">
+  <bean id="killQueue" class="com.imageworks.spcue.dispatcher.HostReportQueue" destroy-method="shutdown" depends-on="cueDataSource,rqdClient">
     <constructor-arg index="0" type="int">
       <value>${kill_queue.threadPoolSizeInitial}</value>
     </constructor-arg>