fix(seer): Align project grouping record deletion with Seer API

[sentry]

Issue: https://sentry.sentry.io/issues/5865067343/?project=1&query=is%3Aunresolved&referrer=issue-stream&statsPeriod=7d
This PR addresses the seer.delete_grouping_records.project.failure errors, which saw a significant spike recently.

The root cause was a mismatch in how Sentry was calling the Seer API endpoint for deleting grouping records by project (/v0/issues/similar-issues/grouping-record/delete).

Specifically, two issues were identified:

1. Incorrect HTTP Method: Sentry was sending a POST request, while the Seer endpoint was defined as a GET.
2. Incorrect Parameter Location: Sentry was sending the project_id in the request body, but Seer expected it as a path parameter (e.g., /v0/issues/similar-issues/grouping-record/delete/{project_id}).

This change updates the make_delete_grouping_records_by_project_request function in src/sentry/seer/signed_seer_api.py to:

• Use the GET HTTP method.
• Construct the URL with the project_id included as a path parameter.
• Send an empty body, as GET requests typically do not carry a body.

This fix ensures that Sentry correctly communicates with the Seer service for project grouping record deletions, resolving the 404 errors and allowing these background tasks to complete successfully.