MDEV-6211: MariaDB-Galera-server uses 'socat', but 'socat' is not in the dependency list

Xtrabackup-based SST method uses socat. Move it from
Suggests to Depends list.

debian/control

@@ -306,7 +306,7 @@ Description: MariaDB database regression test suite
 
 Package: mariadb-server-10.1
 Architecture: any
-Suggests: mailx, mariadb-test, netcat-openbsd, socat, tinyca
+Suggests: mailx, mariadb-test, netcat-openbsd, tinyca
 Recommends: libhtml-template-perl
 Pre-Depends: mariadb-common, adduser (>= 3.40), debconf
 Depends: bsdutils,
@@ -325,6 +325,7 @@ Depends: bsdutils,
          perl (>= 5.6),
          psmisc,
          rsync,
+         socat,
          tar,
          ${misc:Depends},
          ${shlibs:Depends}