Update license secret template to optionally create secret if provided via...

General MR

Summary

• Update license secret template to optionally create secret if provided via helm values. If not provided, use existing secret provided by user, if enterprise is enabled.
• This MR is also accompanied by a Big Bang umbrella MR to remove enterprise enabled in our test values. Enterprise was previously enabled just to enable the serviceMonitor and Grafana Dashboard to deploy. These are now deployable based on just the monitoring toggle being set to enabled.
• fixes/removes stale links, updates docs

Relevant logs/screenshots

I validated that mattermost deploys with enterprise enabled or disabled - and does not create a secret without license being populated. This should not disrupt existing deployments that provide license via helm values.

Linked Issue

issue

Closes #259 (closed)

Closes #240 (closed)

Umbrella Branch

mattermost-updates

Upgrade Notices

Mattermost license secret can now be provided as an existing secret rather than provided via helm values. Remove license value and provide the mattermost package values with addons.mattermost.enterprise.existingSecret. Existing method of creating license secret via helm values will continue to work without interruption.

```

addons:
  mattermost:
    enterprise:
      enabled: true
      existingSecret: <insertExistingSecretName>

```