New dedicated user for Galera SST synchronization

When the Galera is configured to use mariabackup, the
synchronization takes place by connecting to the
database with configuratble user credentials.
Generate a random password for this use case.

Related-Bug: #1973872

Change-Id: I1509bd30fbd253790b17e04ef15dca6c58de7311

tripleo_common/constants.py

@@ -68,6 +68,7 @@ PASSWORD_PARAMETER_NAMES = (
     'KeystonePassword',
     'ManilaPassword',
     'MysqlClustercheckPassword',
+    'MysqlMariabackupPassword',
     'MysqlRootPassword',
     'NeutronMetadataProxySharedSecret',
     'NeutronPassword',
@@ -108,6 +109,7 @@ DB_PASSWORD_PARAMETER_NAMES = (
     'KeystonePassword',
     'ManilaPassword',
     'MysqlClustercheckPassword',
+    'MysqlMariabackupPassword',
     'MysqlRootPassword',
     'NeutronPassword',
     'NovaPassword',
@@ -131,6 +133,7 @@ DO_NOT_ROTATE_LIST = (
     'CephRgwKey',
     'HeatAuthEncryptionKey',
     'MysqlClustercheckPassword',
+    'MysqlMariabackupPassword',
     'PacemakerRemoteAuthkey',
     'PcsdPassword',
 )

tripleo_common/tests/utils/test_plan.py

@@ -112,6 +112,7 @@ _EXISTING_PASSWORDS = {
     'SwiftPassword': 'z6EWAVfW7CuxvKdzjWTdrXCeg',
     'HeatPassword': 'bREnsXtMHKTHxt8XW6NXAYr48',
     'MysqlClustercheckPassword': 'jN4RMMWWJ4sycaRwh7UvrAtfX',
+    'MysqlMariabackupPassword': 'w3qjjJDTKajthzuRYVd4X5YVU',
     'CephClientKey': b'AQCQXtlXAAAAABAAKyc+8St8i9onHyu2mPk+vg==',
     'NeutronPassword': 'ZxAjdU2UXCV4GM3WyPKrzAZXD',
     'DesignatePassword': 'wHYj7rftFzHMpJKnGxbjjR9CW',