coverage: fix centipede using too much disk space

Change-Id: I164f118b0d51af3f80730512c8cf637f9c43c8b4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6431675
Reviewed-by: Ali Hijazi <ahijazi@chromium.org>
Auto-Submit: Paul Semel <paulsemel@chromium.org>
Commit-Queue: Paul Semel <paulsemel@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1442699}
NOKEYCHECK=True
GitOrigin-RevId: dca1a20677386f2e79194c5cb006008325c2422b