Remove duplicate key from cluster spec

To avoid YAML linter warnings in the editor

Author: stankevich

test/endtoend/operator/cluster_upgrade.yaml

@@ -103,7 +103,6 @@ spec:
             mysqldExporter:
               extraFlags:
                 collect.info_schema.tables.databases: "*" # Override operator default
-                collect.info_schema.innodb_cmpmem: "true" # Duplicate flag, overriden below
                 collect.info_schema.innodb_cmpmem: "false"
                 collect.info_schema.tables: "true"
             dataVolumeClaimTemplate: