Fix pattern file naming: rename *.tavern.pat.json to *.pat.json

Pattern files were incorrectly named with .tavern.pat.json extension.
They should be .pat.json to match the test file names correctly.

- Renamed 42 pattern files across database_api_negative, follow_api_negative,
  postgrest_negative, and rest_api_negative directories
- Tests now pass with correctly named pattern files