Fix: Remove default value for region/location from modules

[imVipul3000]

PR for Issue #2003

Checklist

I applicable, I acknowledge that I have:

• Read the contributing guide
• Ran terraform fmt on all modified files
• Regenerated the relevant README.md files using tools/tfdoc.py
• [X} Made sure all relevant tests pass

[wiktorn]

Thank you for picking up this @imVipul3000. If we will have default = null as you propose, we will offload that decision to provider or API. I prefer to ask the user for explicit decision here and remove the default = ... lines at all.

[ludoo]

Closing this as it's become stale, feel free to reopen once the suggestions have been implemented.