[Fix] Add validation for `run_as_mode` in `databricks_query`

[alexott]

Changes

Resolves #4228

Tests

• [x] make test run locally
• [x] relevant change in docs/ folder
• [ ] covered with integration tests in internal/acceptance
• [ ] relevant acceptance tests are passing
• [ ] using Go SDK

[github-actions[bot]]

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger: go/deco-tests-run/terraform

Inputs:

• PR number: 4233
• Commit SHA: bf68d298d8ec831ea256dd6013d671aa259cdf0e

Checks will be approved automatically on success.

[eng-dev-ecosystem-bot]

Test Details: go/deco-tests/11859372499