Deprecate createIndex method

[aulorbe]

Problem

Now that we have the new create index methods (createPodsIndex and createServerlessIndex), we need to deprecate createIndex and update the places in which it's used throughout the codebase.

Related ticket: https://app.asana.com/0/1203260648987893/1206994598304493/f

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update
• [ ] Infrastructure change (CI configs, etc)
• [ ] Non-code change (docs, etc)
• [ ] None of the above: (explain here)

Test Plan

All unit tests and integration tests are running successfully locally. 🤞 CI/CD behaves!

Will do a quick follow with a PR to update the README accordingly.

[aulorbe]

Merging even though the happy path integration test is failing b/c it's a known flakiness error and I have cleared it with @rohanshah18 over Slack. Onwards!