Remote xcresult runs no longer drop or randomly omit test cases

Remote-processed xcresult runs were silently storing partial, non-deterministic test results. On one large plan only 371 of 24,883 cases landed on one upload and 0 or 636 on re-uploads of the same run. The cause: the least-privilege tuist_processor Postgres role was missing SELECT on webhook_endpoints, so any run introducing a new test case on the default branch aborted ingestion mid-loop and the Oban job was discarded after retrying. The processor’s per-table grants are now applied at migrate time and explicitly include webhook_endpoints, so future runs ingest all cases and re-uploads are deterministic.