[sonic-cfggen]: Optimize template rendering and database access. (#17740

)

#### Why I did it
* Improved switch init time

### How I did it
* Replaced: `sonic-cfggen` -> `sonic-db-cli`
* Aggregated template list for `sonic-cfggen`

#### How to verify it
1. Run `warm-reboot`

dockers/docker-database/docker-database-init.sh

@@ -63,8 +63,9 @@ if [[ $DATABASE_TYPE == "chassisdb" ]]; then
     echo "Init docker-database-chassis..."
     update_chassisdb_config -j $db_cfg_file_tmp -k -p $chassis_db_port
     # generate all redis server supervisord configuration file
-    sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/supervisord.conf.j2 > /etc/supervisor/conf.d/supervisord.conf
-    sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/critical_processes.j2 > /etc/supervisor/critical_processes
+    sonic-cfggen -j $db_cfg_file_tmp \
+    -t /usr/share/sonic/templates/supervisord.conf.j2,/etc/supervisor/conf.d/supervisord.conf \
+    -t /usr/share/sonic/templates/critical_processes.j2,/etc/supervisor/critical_processes
     rm $db_cfg_file_tmp
     exec /usr/local/bin/supervisord
     exit 0
@@ -81,8 +82,9 @@ then
 fi
 # delete chassisdb config to generate supervisord config
 update_chassisdb_config -j $db_cfg_file_tmp -d
-sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/supervisord.conf.j2 > /etc/supervisor/conf.d/supervisord.conf
-sonic-cfggen -j $db_cfg_file_tmp -t /usr/share/sonic/templates/critical_processes.j2 > /etc/supervisor/critical_processes
+sonic-cfggen -j $db_cfg_file_tmp \
+-t /usr/share/sonic/templates/supervisord.conf.j2,/etc/supervisor/conf.d/supervisord.conf \
+-t /usr/share/sonic/templates/critical_processes.j2,/etc/supervisor/critical_processes
 
 if [[ "$start_chassis_db" != "1" ]] && [[ -z "$chassis_db_address" ]]; then
      cp $db_cfg_file_tmp $db_cfg_file

dockers/docker-orchagent/docker-init.j2

@@ -23,8 +23,8 @@ CFGGEN_PARAMS=" \
     -t /usr/share/sonic/templates/wait_for_link.sh.j2,/usr/bin/wait_for_link.sh \
 "
 VLAN=$(sonic-cfggen $CFGGEN_PARAMS)
-SUBTYPE=$(sonic-cfggen -d -v "DEVICE_METADATA['localhost']['subtype']")
-SWITCH_TYPE=${SWITCH_TYPE:-`sonic-cfggen -d -v "DEVICE_METADATA['localhost']['switch_type']"`}
+SUBTYPE=$(sonic-db-cli -s CONFIG_DB HGET 'DEVICE_METADATA|localhost' 'subtype')
+SWITCH_TYPE=${SWITCH_TYPE:-`sonic-db-cli -s CONFIG_DB HGET 'DEVICE_METADATA|localhost' 'switch_type'`}
 chmod +x /usr/bin/wait_for_link.sh
 
 # Executed platform specific initialization tasks.