GCP Filestore CSI multishare option support

Epic Goal*

The goal of this epic is to support the Filstore CSI "multishare" option that allows to consume a enterprise filestore instance.

https://cloud.google.com/filestore/docs/multishares

This requires an enterprise tier instance on the GCP side and a specific SC parameter. The CSI driver has to be started with a specific option to enable the multishare feature.

 
Why is this important? (mandatory)

Filestore multishares for GKE allocates up to 80 shares across a single enterprise-tier instance.

This capability optimizes share usage within the Filestore instances and provides the following benefits:

• Gives users the control to estimate and set maximum share capacity
• Optimizes the number of shares per instance
• Optimizes the use of Filestore instances in their associated GKE storage pools
• Improves cost

 
Scenarios (mandatory) 

Provide details for user scenarios including actions to be performed, platform specifications, and user personas.  

1. As an admin I would like to leverage GCP filestore mutishare feature in order to leverage the cost benefit and optimise the use of filestore instances. 

 
Dependencies (internal and external) (mandatory)

There may be a dependency on the way our GCP account are set.

Contributing Teams(and contacts) (mandatory) 

Our expectation is that teams would modify the list below to fit the epic. Some epics may not need all the default groups but what is included here should accurately reflect who will be involved in delivering the epic.

• Development - STOR
• Documentation - STOR
• QE - STOR
• PX - 
• Others -

Acceptance Criteria (optional)

Run the usual CI with the "multishare" option on in the SC. Identify any gaps or regression. If any decide if this is productisable as is it or just document them.

Done - Checklist (mandatory)

The following points apply to all epics and are what the OpenShift team believes are the minimum set of criteria that epics should meet for us to consider them potentially shippable. We request that epic owners modify this list to reflect the work to be completed in order to produce something that is potentially shippable.

• CI Testing -  Basic e2e automationTests are merged and completing successfully
• Documentation - Content development is complete.
• QE - Test scenarios are written and executed successfully.
• Technical Enablement - Slides are complete (if requested by PLM)
• Engineering Stories Merged
• All associated work items with the Epic are closed
• Epic status should be “Release Pending”