Remove patches of upstream HELM charts in StarlingX

[Greg Waines]

Brief Description
-----------------
We are currently carrying a number of patches to upstream HELM charts in StarlingX, related to support for an authenticated registry.

Specifically:
- in stx-openstack, ALL OpenStack services' helm charts have been modified to contain an ImagePullSecret for the registry credentials,
- in stx-monitoring, ELASTIC helm charts have been modified to contain an ImagePullSecret for the registry credentials,
- in platform-integ-apps, (I believe) there are RBD helm chart(s) which have been modified to contain an ImagePullSecret for the registry credentials.

StarlingX should NOT be carrying any patches of upstream projects.

OTHER NOTES:

- for the OpenStack Helm charts,
  in 2019, there was a SPEC submitted and approved for how to address this thru updates to
  the helm toolkit in OpenStack-Helm.
  SPEC: https://review.opendev.org/#/c/651587/

  There have been some attempts to work on this, but not a lot of progress.
  SEE: https://review.opendev.org/#/c/651585/

- for Elastic and RBD Helm Charts,
  will require upstream changes to these helm charts

Severity
--------
<Major: System/Feature is usable but degraded>

Steps to Reproduce
------------------
N/A

Expected Behavior
------------------
Be able to use upstream helm charts with a helm-override-values.yaml to specify the specific secret containing the ImagePullSecret.

Actual Behavior
----------------
There is a patch in starlingx to introduce an ImagePullSecret in the helm charts.

Reproducibility
---------------
<Reproducible>
100% reproducible

System Configuration
--------------------
N/A

Branch/Pull Time/Commit
-----------------------
Since R2.

Last Pass
---------
Never passed.

Timestamp/Logs
--------------
N/A

Test Activity
-------------
[Developer Testing]

 Workaround
 ----------
 The patches.

[Ghada Khalil (gkhalil)]

Need to engage with the helm community to enable the required support upstream.
In terms of stx releases, we wouldn't consider this gating given we are applying our own patches, but longer term, we would like to have the required support upstream.

Assigning to the containers PL to determine next steps and timeline