tests: defines aliases for `hg log` calls in test-copytrace-heuristics.t

Authored by martinvonz.

Description

tests: defines aliases for hg log calls in test-copytrace-heuristics.t

This also makes the test cases more consistent since a few had missed
the ":" in "changeset:" that the others used.

Differential Revision: https://phab.mercurial-scm.org/D6278