MDEV-25681: --relay-log{,-index} missing warning

No longer a MySQL server, "his" is the wrong pronoun
for a server.

Thanks Michael Newton for highlighting these problems

Also changed slave -> replica.

sql/rpl_rli.cc

@@ -203,8 +203,8 @@ a file name for --relay-log-index option", opt_relaylog_index_name);
       */
       sql_print_warning("Neither --relay-log nor --relay-log-index were used;"
                         " so replication "
-                        "may break when this MySQL server acts as a "
-                        "slave and has his hostname changed!! Please "
+                        "may break when this MariaDB server acts as a "
+                        "replica and has its hostname changed. Please "
                         "use '--log-basename=#' or '--relay-log=%s' to avoid "
                         "this problem.", ln);
       name_warning_sent= 1;