Merge branch 'ps/ref-tests-update-even-more'

More tests that are marked as "ref-files only" have been updated to improve test coverage of reftable backend. * ps/ref-tests-update-even-more: t7003: ensure filter-branch prunes reflogs with the reftable backend t2011: exercise D/F conflicts with HEAD with the reftable backend t1405: remove unneeded cleanup step t1404: make D/F conflict tests compatible with reftable backend t1400: exercise reflog with gaps with reftable backend t0410: convert tests to use DEFAULT_REPO_FORMAT prereq t: move tests exercising the "files" backend