Make galera-3 a Recommends instead of Depends in Debian packaging

Having galera-3 as a Depends stops installation of proceeding
on systems where package galera-3 is not available. The server
can run fine withouth galera enabled, therefore a more slack
relationship is more appropriate.

debian/control

@@ -271,12 +271,11 @@ Description: MariaDB database regression test suite
 Package: mariadb-server-10.1
 Architecture: any
 Suggests: mailx, mariadb-test, netcat-openbsd, socat, tinyca
-Recommends: libhtml-template-perl
+Recommends: libhtml-template-perl, galera-3 (>=25.3)
 Pre-Depends: mariadb-common, adduser (>= 3.40), debconf
 Depends: bsdutils,
          coreutils,
          findutils,
-         galera-3 (>=25.3),
          gawk,
          grep,
          iproute,