Generate initial cluster file based on "CoordinatorSelection"

[sbodagala]

Description

Modify the initial cluster file sub reconciler to make use of the coordinator selection mechanism. And, update the affected tests.

Addresses issue: #1089

Type of change

• New feature (non-breaking change which adds functionality)

Discussion

• Does the current operator logic always select storage processes as coordinators? If so, this PR may cause log processes to also be selected as coordinators? And, if so, what is the impact of that during recovery? So, overall, is this a good change?

Testing

Ran the operator unit tests successfully (by doing "make fmt lint test").

Documentation

TBD: Do we need to update any documentation?

Follow-up

[foundationdb-ci]

Result of fdb-kubernetes-operator-pr on Linux CentOS 7

• Commit ID: 230dfc4
• Duration 2:02:18
• Result: ❌ FAILED
• Error: Error while executing command: if $fail_test; then exit 1; fi. Reason: exit status 1
• Build Log terminal output (available for 30 days)
• Build Workspace zip file of the working directory (available for 30 days)

[johscheuer]

We are doing now more calls to the Kubernetes API (or the local cache), that could be prevented by using a label selector that selects multiple process classes but that would be an optimisation, that is only relevant in the initial cluster create phase so 👍 for the simplicity.

Thanks!