Galera MTR Tests: Run galera_pc_weight on freshly started servers in order to...

Galera MTR Tests: Run galera_pc_weight on freshly started servers in order to prevent interaction with other tests

mysql-test/suite/galera_3nodes/t/galera_pc_weight.cnf

+# We need a dedicated .cnf file, even if empty, in order to force this test to run
+# alone on a freshly started cluster. Otherwise there are adverse interactions with
+# following tests such as galera_3nodes.galera_var_dirty_reads2
+
+!include ../galera_3nodes.cnf