Mattermost operator values secret missing if not explicitly enabled

Mattermost Operator should be enabled implicitly if Mattermost is enabled.

When migrating to bb-common I incorrectly modified the condition by which the values secret for mattermost operator is created to not also consider addons.mattermost.enabled in addition to addons.mattermostOperator.enabled

This results in an error on the mattermost-operator HelmRelease: could not resolve Secret chart values reference ''bigbang/bigbang-mattermost-operator-values'' with key ''common'': secrets "bigbang-mattermost-operator-values" not found if BigBang is deployed with:

addons:
  # note this missing explicit enable of mattermost operator
  mattermost:
    enabled: true
    elasticsearch:
      enabled: false