fix(terraform): gate observability with feature flags

[fbeltrao]

Description

Switch observability resource gating from apply-time dependency object checks to explicit plan-time feature flags.

This change passes should_deploy_monitor_workspace and should_deploy_dce into module.sil, then uses those booleans to control creation of AKS data collection rules and associations. That removes the invalid count expressions that depended on module.platform outputs only known after apply.

The PR also updates the operations guide so the observability feature-flag documentation matches the Terraform behavior:

• Container Insights is gated by should_deploy_dce
• Prometheus metrics rules require both should_deploy_dce and should_deploy_monitor_workspace

Closes #302

Type of Change

• 🐛 Bug fix (non-breaking change fixing an issue)
• ✨ New feature (non-breaking change adding functionality)
• 💥 Breaking change (fix or feature causing existing functionality to change)
• 📚 Documentation update
• 🏗️ Infrastructure change (Terraform/IaC)
• ♻️ Refactoring (no functional changes)

Component(s) Affected

• infrastructure/terraform/prerequisites/ - Azure subscription setup
• infrastructure/terraform/ - Terraform infrastructure
• infrastructure/setup/ - OSMO control plane / Helm
• workflows/ - Training and evaluation workflows
• training/ - Training pipelines and scripts
• docs/ - Documentation

Testing Performed

• Terraform plan reviewed (no unexpected changes)
• Terraform apply tested in dev environment
• Training scripts tested locally with Isaac Sim
• OSMO workflow submitted successfully
• Smoke tests passed (smoke_test_azure.py)

Notes:

• PR description is based on the last commit contents. No additional Terraform validation results were available in the commit metadata, so testing items remain unchecked.

Documentation Impact

• No documentation changes needed
• Documentation updated in this PR
• Documentation issue filed

Bug Fix Checklist

Complete this section for bug fix PRs. Skip for other contribution types.

• Linked to issue being fixed
• Regression test included, OR
• Justification for no regression test: This change fixes Terraform planning logic in infrastructure code. The repository guidance for this area relies on Terraform validation and environment applies rather than automated regression tests for provider planning behavior.

Checklist

• My code follows the project conventions
• Commit messages follow conventional commit format
• I have performed a self-review
• Documentation impact assessed above
• No new linting warnings introduced

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.37%. Comparing base (101a6e8) to head (3a24b96).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #303   +/-   ##
=======================================
  Coverage   38.37%   38.37%           
=======================================
  Files          73       73           
  Lines        8579     8579           
  Branches      497      497           
=======================================
  Hits         3292     3292           
  Misses       5277     5277           
  Partials       10       10           

Flag	Coverage Δ		*Carryforward flag
pester	79.87% <ø> (ø)
pytest	6.89% <ø> (ø)		Carriedforward from d90d66d
pytest-dataviewer	61.98% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[katriendg]

Thanks a lot @fbeltrao - great fix.

In the meantime we have merged in a change to add Terraform tests.
After you rebase, you will have some small updates to infrastructure/terraform/modules/sil/tests, if you then run npm run test:tf and pass locally all should be done. Approving but with the note about this change required before we can merge.

[fbeltrao]

Thanks a lot @fbeltrao - great fix.

In the meantime we have merged in a change to add Terraform tests. After you rebase, you will have some small updates to infrastructure/terraform/modules/sil/tests, if you then run npm run test:tf and pass locally all should be done. Approving but with the note about this change required before we can merge.

Tests are fixed now.