Summary

I previously described the problems and possible solutions in this issue:
#416
mongodb/mongodb-kubernetes-operator#1737

This branch implements the second proposed solution: Context-Aware Default Templates.
The goal is to avoid unnecessary resource waste by providing separate defaults for arbiters vs. data members while keeping customization consistent.

Proof of Work

Implementation:

• Pass an isArbiter boolean to the build function
• Apply arbiter-optimized defaults when isArbiter=true:
  • No PVC
  • Minimal resources
• Maintain current behavior for data members
• Keep spec.statefulSet for member customization only

Checklist

• Have you linked a jira ticket and/or is the ticket in the title?
• Have you checked whether your jira ticket required DOCSP changes?
• [ ✅] Have you added changelog file?
  • use skip-changelog label if not needed
  • refer to Changelog files and Release Notes section in CONTRIBUTING.md for more details