Modify fast-reboot script to use teamd service script (#1251)

A new teamd service script has been added in sonic-buildimage as part of the PR - sonic-net/sonic-buildimage#5163
With this change, fast-reboot script will now use the new teamd script to handle killing teamd docker in both fast-boot and warm-boot mode.

Replaced the existing teamd docker handling in fast-reboot script with the systemctl stop teamd.
Tested the locally modified script in a DUT for warm-reboot and fast-reboot.

scripts/fast-reboot

@@ -542,17 +542,7 @@ docker kill lldp &> /dev/null || debug "Docker lldp is not running ($?) ..."
 systemctl stop lldp
 
 if [[ "$REBOOT_TYPE" = "fast-reboot" ]]; then
- # Kill teamd processes inside of teamd container with SIGUSR2 to allow them to send last LACP frames
- # We call `docker kill teamd` to ensure the container stops as quickly as possible,
- # then immediately call `systemctl stop teamd` to prevent the service from
- # restarting the container automatically.
- # Note: teamd must be killed before syncd, because it will send the last packet through CPU port
  debug "Stopping teamd ..."
- docker exec -i teamd pkill -USR2 teamd || [ $? == 1 ]
- while docker exec -i teamd pgrep teamd > /dev/null; do
- sleep 0.05
- done
- docker kill teamd &> /dev/null || debug "Docker teamd is not running ($?) ..."
  systemctl stop teamd
  debug "Stopped teamd ..."
 fi
@@ -561,8 +551,8 @@ debug "Stopping swss service ..."
 systemctl stop swss
 debug "Stopped swss service ..."
 
-# Pre-shutdown syncd
 if [[ "$REBOOT_TYPE" = "warm-reboot" || "$REBOOT_TYPE" = "fastfast-reboot" ]]; then
+ # Pre-shutdown syncd
  initialize_pre_shutdown
 
  BEFORE_PRE_SHUTDOWN=true
@@ -589,15 +579,10 @@ if [[ "$REBOOT_TYPE" = "warm-reboot" || "$REBOOT_TYPE" = "fastfast-reboot" ]]; t
  # TODO: backup_database preserves FDB_TABLE
  # need to cleanup as well for fastfast boot case
  backup_database
-fi
 
-# Stop teamd gracefully
-if [[ "$REBOOT_TYPE" = "warm-reboot" || "$REBOOT_TYPE" = "fastfast-reboot" ]]; then
+ # Stop teamd gracefully
  debug "Stopping teamd ..."
- # Send USR1 signal to all teamd instances to stop them
- # It will prepare teamd for warm-reboot
- # Note: We must send USR1 signal before syncd, because it will send the last packet through CPU port
- docker exec -i teamd pkill -USR1 teamd > /dev/null || [ $? == 1 ]
+ systemctl stop teamd
  debug "Stopped teamd ..."
 fi