[apache#960][followup] fix(dashboard): Fix get_pid_file_name function…

… for the dashboard. (apache#1346)

### What changes were proposed in this pull request?

Fix get_pid_file_name function for the dashboard.

### Why are the changes needed?

This is the follow up pr of  [apache#1056](apache#1056)

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

By running the script: start-dashboard.sh and stop-dashboard.sh.

bin/start-dashboard.sh

@@ -82,5 +82,5 @@ fi
 
 $RUNNER $ARGS $JVM_ARGS $JAVA11_EXTRA_ARGS -cp $CLASSPATH $MAIN_CLASS --conf "$COORDINATOR_CONF_FILE" $@ &> $OUT_PATH &
 
-get_pid_file_name uniffle-dashboard
+get_pid_file_name dashboard
 echo $! >${RSS_PID_DIR}/${pid_file}

bin/stop-dashboard.sh

@@ -25,4 +25,4 @@ set -o errexit   # exit the script if any statement returns a non-true return va
 source "$(dirname "$0")/utils.sh"
 load_rss_env
 
-common_shutdown "uniffle-dashboard" "${RSS_PID_DIR}"
+common_shutdown "dashboard" "${RSS_PID_DIR}"

bin/utils.sh

@@ -59,14 +59,16 @@ function common_shutdown {
 }
 
 #---
-# args:               Process name, coordinator or shuffle-server
+# args:               Process name, coordinator, shuffle-server or dashboard
 #---
 function get_pid_file_name {
   process_name="$1"
   if [[ $process_name == "coordinator" ]]; then
     pid_file="coordinator.pid"
   elif [[ $process_name == "shuffle-server" ]]; then
     pid_file="shuffle-server.pid"
+  elif [[ $process_name == "dashboard" ]]; then
+    pid_file="dashboard.pid"
   else
     echo "Invalid process name: $process_name"
     exit 1