status tests: filter `.gitconfig` from status output
Since test-lib.sh creates `$HOME/.gitconfig` when `WITH_BREAKING_CHANGES` is in effect, the file appears in `git status` output as either untracked (`?? .gitconfig`) or ignored (`!! .gitconfig` / `! .gitconfig`, depending on porcelain version), because the `.git/info/exclude` entry causes git to treat it as an ignored file rather than hiding it entirely. In t7061 and t7521, which are pervasively affected, introduce a `filter_gitconfig` helper that strips all status-prefix variants of `.gitconfig` from the output before comparison. In the remaining scripts (t7060, t7064, t7508), apply targeted adjustments. Assisted-by: Claude Opus 4.6 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>