tests: fix the flaky test test-logtoprocess.t
The main change is that we're waiting for the [touched] file to appear for 5 seconds instead of 0.1 seconds. Also, instead of implementing wait-on-file from scratch, we use the existing one from testlib/ that works well.
import hashlib
try:
from ..thirdparty import sha1dc # pytype: disable=import-error
sha1 = sha1dc.sha1
except (ImportError, AttributeError):
sha1 = hashlib.sha1