MDEV-8083 MTR is broken on systems with IPv6 disabled

disable IPv6 globally in mysql-test, only use it
in dedicated IPv6 tests (where it is enabled per-test)

mysql-test/include/default_mysqld.cnf

@@ -31,6 +31,7 @@ debug-no-sync
 
 # Retry bind as this may fail on busy server
 port-open-timeout=10
+bind-address=127.0.0.1
 
 log-bin-trust-function-creators=1
 key_buffer_size=            1M

mysql-test/suite/perfschema/t/socket_instances_func-master.opt

@@ -1 +1 @@
---skip-name-resolve
+--skip-name-resolve --bind-address=*