Update plugins.pam_* tests to no longer provide --plugin-dir to mysqltest

Post change of 8447edb747, --plugin-dir
is set in the default my.cnf file under [client]. The value is automatically
detected during mtr startup.

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

@@ -40,19 +40,19 @@ EOF
 --echo # athentication is unsuccessful
 --echo #
 --error 1
---exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_ugly.txt
+--exec $MYSQL_TEST -u test_pam < $MYSQLTEST_VARDIR/tmp/pam_ugly.txt
 
 --echo #
 --echo # athentication is successful
 --echo #
 --error 0
---exec $MYSQL_TEST -u test_pam -pgoodpassword --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
+--exec $MYSQL_TEST -u test_pam -pgoodpassword < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
 
 --echo #
 --echo # athentication is unsuccessful
 --echo #
 --error 1
---exec $MYSQL_TEST -u test_pam -pbadpassword --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
+--exec $MYSQL_TEST -u test_pam -pbadpassword < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
 
 drop user test_pam;
 drop user pam_test;

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

@@ -13,22 +13,22 @@ EOF
 --echo # same test as in pam.test now fails
 --echo #
 --error 1
---exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good.txt
+--exec $MYSQL_TEST -u test_pam < $MYSQLTEST_VARDIR/tmp/pam_good.txt
 --error 1
---exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir -p'something' < $MYSQLTEST_VARDIR/tmp/pam_good.txt
+--exec $MYSQL_TEST -u test_pam -p'something' < $MYSQLTEST_VARDIR/tmp/pam_good.txt
 
 --remove_file $MYSQLTEST_VARDIR/tmp/pam_good.txt
 
 --echo #
 --echo # success
 --echo #
---exec $MYSQL -u test_pam --plugin-dir=$plugindir -p'cleartext good' -e 'select user(), current_user(), database()'
+--exec $MYSQL -u test_pam -p'cleartext good' -e 'select user(), current_user(), database()'
 
 --echo #
 --echo # failure
 --echo #
 --error 1
---exec $MYSQL -u test_pam --plugin-dir=$plugindir -p'cleartext bad' -e 'select user(), current_user(), database()'
+--exec $MYSQL -u test_pam -p'cleartext bad' -e 'select user(), current_user(), database()'
 
 drop user test_pam;
 drop user pam_test;

mysql-test/suite/plugins/t/pam_v1.test

@@ -22,25 +22,25 @@ EOF
 --echo # athentication is successful, challenge/pin are ok
 --echo # note that current_user() differs from user()
 --echo #
---exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good.txt
+--exec $MYSQL_TEST -u test_pam < $MYSQLTEST_VARDIR/tmp/pam_good.txt
 
 --echo #
 --echo # athentication is unsuccessful
 --echo #
 --error 1
---exec $MYSQL_TEST -u test_pam --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_bad.txt
+--exec $MYSQL_TEST -u test_pam < $MYSQLTEST_VARDIR/tmp/pam_bad.txt
 
 --echo #
 --echo # athentication is successful
 --echo #
 --error 0
---exec $MYSQL_TEST -u test_pam -pgoodpassword --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
+--exec $MYSQL_TEST -u test_pam -pgoodpassword < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
 
 --echo #
 --echo # athentication is unsuccessful
 --echo #
 --error 1
---exec $MYSQL_TEST -u test_pam -pbadpassword --plugin-dir=$plugindir < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
+--exec $MYSQL_TEST -u test_pam -pbadpassword < $MYSQLTEST_VARDIR/tmp/pam_good2.txt
 
 --remove_file $MYSQLTEST_VARDIR/tmp/pam_good.txt
 --remove_file $MYSQLTEST_VARDIR/tmp/pam_good2.txt