MDEV-31242: Make sure every Debian post/pre script is using bash

Make sure that every post and pre script are using bash
and have set -e in next to shebang.

Command set -e makes sure that if script fails in
one command it will fail whole script.

debian/mariadb-common.postinst

-#!/bin/sh
+#!/bin/bash
 
 set -e
 

debian/mariadb-common.postrm

-#!/bin/sh
+#!/bin/bash
 
 set -e
 

debian/mariadb-plugin-mroonga.postinst

-#!/bin/sh
+#!/bin/bash
 
 set -e
 

debian/mariadb-plugin-mroonga.prerm

-#!/bin/sh
+#!/bin/bash
 
 set -e
 

debian/mariadb-server.preinst

-#!/bin/bash -e
+#!/bin/bash
 #
 # summary of how this script can be called:
 #        * <new-preinst> install
@@ -7,6 +7,8 @@
 #        * <old-preinst> abort-upgrade <new-version>
 #
 
+set -e
+
 # shellcheck source=/dev/null
 . /usr/share/debconf/confmodule
 

debian/mariadb-server.prerm

-#!/bin/sh
+#!/bin/bash
 set -e
 
 #DEBHELPER#