Fetch pipelines from main branch in driver-trace-stats

Instead of fetching pipelines since a date, let's bring the pipelines from the recent commits that are de facto in the remote main branch.

The old method brings only looked for pipelines created by Marge and succeeded. But if the pipeline with timeouts from Marge, they are still green from the Gitlab perspective. So, this listing can bring some pipelines in bad shape, which may affect the performance results variance.

E.g:

• unstable updates in dependencies
  • dependencies uprevs pipelines take much longer due to rootfs rebuild, and they are prone to Marge timeouts
• eager optimizations that worked in one driver but made another very slow, etc.

Note

I did not change scripts which populate the following dashboards:

• https://grafana.freedesktop.org/d/IEx7qSP7z/marge-triggered-job-status-per-stage?orgId=1
• https://grafana.freedesktop.org/d/-UCa0si7z/mesa-ci-stats?orgId=1

Since they need all MR pipelines from Marge, not only the successful ones that were merged to main branch.