Fix sending SIGTERM to the sidecar containers

This is "repeat" of the Nate's fix done for stable/train branch in
[1].
This patch had got one issue - it missed passing "15" signal to the
signal_container() function and due to that e.g. keepalived sidecar
container wasn't never killed when router was deleted.

Patch [1] was recently removed with patch [2] so now I need to get it
back in the kill-script.

New version of the kill-script is in tripleo-ansible in the
tripleo-systemd-wrapper role where all is done fine and "15" signal is
passed properly to the signal_container() function.

[1] https://review.opendev.org/#/c/704463/
[2] https://review.opendev.org/#/c/724843/

Change-Id: I3f18922cf58bf8359f27aebf295bdb131bf2333a
Closes-bz: #1839071

deployment/neutron/kill-script

@@ -40,9 +40,13 @@ kill_container() {
   $CLI rm $2
 }
 
-hup_container() {
-  add_date "Sending HUP signal to $1 ($2)"
-  $CLI kill --signal HUP $2
+signal_container() {
+  SIGNAL=$3
+  if [ -z "$SIGNAL" ]; then
+      SIGNAL="HUP"
+  fi
+  add_date "Sending signal '$SIGNAL' to $1 ($2)"
+  $CLI kill --signal $SIGNAL $2
 }
 
 {% raw -%}
@@ -53,13 +57,16 @@ if [ -f /proc/$PID/cgroup ]; then
 
   case $SIG in
     HUP)
-      hup_container $CT_NAME $CT_ID
+      signal_container $CT_NAME $CT_ID
       ;;
     9)
       kill_container $CT_NAME $CT_ID
       ;;
+    15)
+      signal_container $CT_NAME $CT_ID 15
+      ;;
     *)
-      add_date "Unknown action ${SIG} for ${$CT_NAME} ${CT_ID}"
+      add_date "Unknown action ${SIG} for ${CT_NAME} ${CT_ID}"
       exit 1
       ;;
   esac