MDEV-30952: Reformat Debian post and pre scripts

There is several misindentation inside Debian post and pre
installation scripts. False indentation with space
as indent space should be 2 and indentation with tabs.

debian/mariadb-server-10.6.postinst

@@ -265,7 +265,7 @@ fi
 if [ -d /run/systemd/system ]; then
   systemctl --system daemon-reload >/dev/null || true
   deb-systemd-invoke start mariadb.service >/dev/null || true
-# Modified dh_installinit snippet to only run with sysvinit
+  # Modified dh_installinit snippet to only run with sysvinit
 elif [ -x "/etc/init.d/mariadb" ]; then
   if [ "$1" = "configure" ] || [ "$1" = "abort-upgrade" ]; then
     invoke-rc.d mariadb start || exit $?

debian/mariadb-server-10.6.prerm

@@ -6,7 +6,7 @@ set -e
 # Modified dh_systemd_start snippet that's not added automatically
 if [ -d /run/systemd/system ]; then
   deb-systemd-invoke stop mariadb.service >/dev/null
-# Modified dh_installinit snippet to only run with sysvinit
+  # Modified dh_installinit snippet to only run with sysvinit
 elif [ -x "/etc/init.d/mariadb" ]; then
   invoke-rc.d mariadb stop || exit $?
 fi