[SPARK-23491][SS] Remove explicit job cancellation from ContinuousExecution reconfiguring

## What changes were proposed in this pull request?

Remove queryExecutionThread.interrupt() from ContinuousExecution. As detailed in the JIRA, interrupting the thread is only relevant in the microbatch case; for continuous processing the query execution can quickly clean itself up without.

## How was this patch tested?

existing tests

Author: Jose Torres <jose@databricks.com>

Closes #20622 from jose-torres/SPARK-23441.

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/continuous/ContinuousExecution.scala

@@ -236,9 +236,7 @@ class ContinuousExecution(
             startTrigger()
 
             if (reader.needsReconfiguration() && state.compareAndSet(ACTIVE, RECONFIGURING)) {
-              stopSources()
               if (queryExecutionThread.isAlive) {
-                sparkSession.sparkContext.cancelJobGroup(runId.toString)
                 queryExecutionThread.interrupt()
               }
               false
@@ -266,12 +264,20 @@ class ContinuousExecution(
         SQLExecution.withNewExecutionId(
           sparkSessionForQuery, lastExecution)(lastExecution.toRdd)
       }
+    } catch {
+      case t: Throwable
+          if StreamExecution.isInterruptionException(t) && state.get() == RECONFIGURING =>
+        logInfo(s"Query $id ignoring exception from reconfiguring: $t")
+        // interrupted by reconfiguration - swallow exception so we can restart the query
     } finally {
       epochEndpoint.askSync[Unit](StopContinuousExecutionWrites)
       SparkEnv.get.rpcEnv.stop(epochEndpoint)
 
       epochUpdateThread.interrupt()
       epochUpdateThread.join()
+
+      stopSources()
+      sparkSession.sparkContext.cancelJobGroup(runId.toString)
     }
   }