Don't use "-c" flag in "git:branch-unique()" revision range rule

Summary:
Fixes T9953.

• "-c" was introduced in 1.7.2.
• "--no-color" has existed forever as far as I can tell.
• "--no-column" was introducd in 1.7.11, but there was nothing that needed to be disabled before that (hopefully).

Test Plan:

• Ran arc which --trace and observed a reasonable git branch command with correct output.
• Ran arc which --trace with a faked older Git version, observed command omit --no-column.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9953

Differential Revision: https://secure.phabricator.com/D14735