Fix name override issues

[olim7t]

What this PR does:
1) Handle the case where a DC's metadata.name cannot be used directly as a Kubernetes resource name:

datacenters:
   - metadata:
      name: Data_Center_1

I changed the validation webhook to reject this. I think this is the best solution because we already provide the datacenterName override for cases where the CQL name couldn't be used here. We could sanitize metadata.name when it's not valid, but that would bring even more confusion IMO.

2) Fix the naming of some secondary resources (ConfigMaps, etc.) that were incorrectly using the unsanitized override. For example, given:

datacenters:
  - metadata:
    name: dc1
  datacenterName: Data_Center_1

The operator would generate resource names such as ...-Data_Center_1-metrics-agent-config which is obviously wrong. I've changed those to sanitize the override: ...-data-center-1-metrics-agent-config.

On a related note, I also fixed the metrics agent configMap, which was using the wrong cluster name.

Which issue(s) this PR fixes:
Fixes #1141
Fixes #1138

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CHANGELOG.md updated (not required for documentation PRs)
• CLA Signed: DataStax CLA

[codecov]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 57.43%. Comparing base (8189711) to head (f6c4330).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1246      +/-   ##
==========================================
- Coverage   57.45%   57.43%   -0.02%     
==========================================
  Files         103      103              
  Lines       10794    10801       +7     
==========================================
+ Hits         6202     6204       +2     
- Misses       4057     4060       +3     
- Partials      535      537       +2     

Files	Coverage Δ
...pis/k8ssandra/v1alpha1/k8ssandracluster_webhook.go	72.72% <100.00%> (+1.45%)	⬆️
...ollers/k8ssandra/cassandra_telemetry_reconciler.go	63.63% <100.00%> (ø)
controllers/k8ssandra/per_node_config.go	56.75% <100.00%> (ø)
pkg/nodeconfig/generate.go	100.00% <100.00%> (ø)
pkg/reaper/vector.go	63.63% <100.00%> (ø)
pkg/stargate/deployments.go	92.96% <100.00%> (ø)
pkg/stargate/vector.go	63.63% <100.00%> (ø)
pkg/telemetry/vector.go	97.76% <100.00%> (ø)
...elemetry/cassandra_agent/cassandra_agent_config.go	24.24% <75.00%> (+2.36%)	⬆️

... and 4 files with indirect coverage changes

[olim7t]

I don't think the CI issue is related. I didn't touch anything related to backup/restore, and it's also timing out on main.

[emerkle826]

👍

[emerkle826]

@olim7t Need to add a Changelog entry too I guess

[sonarcloud]

Quality Gate failed

Failed conditions
3.2% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud