Profiles: Stop passing response headers for Grafana-Pyroscope and parca datasources (#106577)
* Revert "pkgs/tsdb/[grafana-pyroscope-datasource|parca]: Fix use of request headers in responses"
This reverts commit 8bac68e906.
* Profiles: Stop passing request/response headers to the backend
(cherry picked from commit 8fdf86e56f)
(cherry picked from commit 7878815ffc)