[PLAT-14848] postgres.service file did not have RestartSec filled out

Summary:
The template used for postgres.service had an incorrect yaml path
for getting the restart seconds value from yba-ctl.yml. Updated to
postgres.install.restartSeconds

Test Plan: validated service file is correct

Reviewers: muthu, sanketh

Reviewed By: muthu

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D37061

managed/yba-installer/config/templates/yba-installer-postgres.yml

@@ -22,7 +22,7 @@
       -w -o "-k {{ .MountPath }}" -l {{ .LogFile }} stop
 
       Restart=always
-      RestartSec={{ yamlPath "postgres.restartSeconds"}}
+      RestartSec={{ yamlPath "postgres.install.restartSeconds"}}
 
       [Install]
       WantedBy=multi-user.target