Switch to querying new tests results DB (#5616)

## Problem

We started to store test results in a new format in
https://github.com/neondatabase/neon/pull/4549.
This PR switches scripts to query this db.

(we can completely remove old DB/ingestions scripts in a couple of
weeks after the PR merged)

## Summary of changes
- `scripts/benchmark_durations.py` query new database
- `scripts/flaky_tests.py` query new database

.github/actions/allure-report-generate/action.yml

@@ -203,6 +203,10 @@ runs:
         COMMIT_SHA: ${{ github.event.pull_request.head.sha || github.sha }}
         BASE_S3_URL: ${{ steps.generate-report.outputs.base-s3-url }}
       run: |
+        if [ ! -d "${WORKDIR}/report/data/test-cases" ]; then
+          exit 0
+        fi
+
         export DATABASE_URL=${REGRESS_TEST_RESULT_CONNSTR_NEW}
 
         ./scripts/pysync