sanitize-commit: recognize tqtc/wip/ branches as work-in-progress

The pickbot "on dev" test suppresses the "Omission of Pick-to footer"
nagging for wip/ branches, but the target check only matched a leading
"wip/". A TQtC-private (tqtc-) repository mirrors the public branches
under their plain names and reserves the "tqtc/" prefix for branches that
exist only there, so the WIP counterpart of a public "wip/foo" is
"tqtc/wip/foo" -- which never matched the bypass. WIP changes on such a
branch were therefore nagged to add a Pick-to footer they do not want,
and dropping the prefix is no workaround, as the mirror would prune the
branch.

Accept an optional "tqtc/" prefix so tqtc/wip/* branches get the same WIP
treatment as public wip/* branches. A bare tqtc/ (non-wip) branch, e.g.
tqtc/modernization, is unaffected and still nags. The $masterName
comparison deliberately keeps matching the plain name only; see the
comment added next to it.

Change-Id: I656c7b6f863e5c2452b33f0f8b54d9d185f44c07
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Reviewed-by: Daniel Smith <daniel.smith@qt.io>