Motivating commit: https://github.com/wiredtiger/wiredtiger/pull/11579/commits/f140f8508e0219fff1a8e80b7d318219e54d4989

When we reduced the frequency of truncates in test_live_restore.cpp from 0.2% down to 0.02% we started to hit  No space left on device errors. Reverting back to 0.2% stops it from firing, but in rare cases we could still hit this issue.

This ticket is to add logic in the test that prevents us from writing enough data to exhaust disk space.