fix plugin.multiauth test for FreeBSD

remove AIX support, as 10.4 is not tested on AIX, so cannot test a regex

mysql-test/suite/plugins/r/multiauth,aix.rdiff

-diff --git a/mysql-test/suite/plugins/r/multiauth.result b/mysql-test/suite/plugins/r/multiauth.result
-index aed46ac8964..24bb0a24f03 100644
---- a/mysql-test/suite/plugins/r/multiauth.result
-+++ b/mysql-test/suite/plugins/r/multiauth.result
-@@ -181,7 +181,8 @@ show create user mysqltest1;
- CREATE USER for mysqltest1@%
- CREATE USER `mysqltest1`@`%` IDENTIFIED VIA ed25519 USING 'F4aF8bw7130VaRbdLCl4f/P/wkjDmgJXwWvpJ5gmsZc'
- # no plugin = failure
--mysqltest: Could not open connection 'default': 1045 Plugin client_ed25519 could not be loaded: <PLUGINDIR>/no/client_ed25519.so: cannot open shared object file: No such file or directory
-+mysqltest: Could not open connection 'default': 1045 Plugin client_ed25519 could not be loaded: Could not load module <PLUGINDIR>/no/client_ed25519.so.
-+System error: No such file or directory
- alter user mysqltest1 identified via ed25519 as password("good") OR mysql_native_password as password("works");
- show create user mysqltest1;
- CREATE USER for mysqltest1@%

mysql-test/suite/plugins/r/multiauth.result

@@ -180,7 +180,7 @@ show create user mysqltest1;
 CREATE USER for mysqltest1@%
 CREATE USER `mysqltest1`@`%` IDENTIFIED VIA ed25519 USING 'F4aF8bw7130VaRbdLCl4f/P/wkjDmgJXwWvpJ5gmsZc'
 # no plugin = failure
-mysqltest: Could not open connection 'default': 1045 Plugin client_ed25519 could not be loaded: <PLUGINDIR>/no/client_ed25519.so: cannot open shared object file: No such file or directory
+mysqltest: Could not open connection 'default': 1045 Plugin client_ed25519 could not be loaded: no such file
 alter user mysqltest1 identified via ed25519 as password("good") OR mysql_native_password as password("works");
 show create user mysqltest1;
 CREATE USER for mysqltest1@%

mysql-test/suite/plugins/t/multiauth.test

 --source include/not_ubsan.inc
---source include/platform.inc
 #
 # MDEV-11340 Allow multiple alternative authentication methods for the same user
 #
@@ -182,7 +181,7 @@ eval $dreplace, mysqltest1;
 create user mysqltest1 identified via ed25519 as password("good");
 show create user mysqltest1;
 --echo # no plugin = failure
---replace_result $plugindir <PLUGINDIR>
+--replace_regex /loaded: .*client_ed25519.so: cannot open shared object file: No such file or directory/loaded: no such file/ /loaded: Cannot open.*client_ed25519.so./loaded: no such file/
 --error 1
 --exec $try_auth -u mysqltest1 -pgood --plugin-dir=$plugindir/no
 alter user mysqltest1 identified via ed25519 as password("good") OR mysql_native_password as password("works");