Fix the slow start of mariadb container

Adding '-e MYSQL_INITDB_SKIP_TZINFO=1' when starting database
container.

Ref:
https://github.com/docker-library/mariadb/issues/262

Change-Id: I3398557700dd76ec831e441ba074032fd4b67cca

trove/guestagent/datastore/mysql_common/service.py

@@ -626,6 +626,7 @@ class BaseMySqlApp(object):
                 user=user,
                 environment={
                     "MYSQL_ROOT_PASSWORD": root_pass,
+                    "MYSQL_INITDB_SKIP_TZINFO": 1,
                 },
                 command=command
             )