featureflag: Remove the `CatfileBatchCommand` flag
The CatfileBatchCommand
flag was used to rollout the --batch-command
option of git-cat-file(1)
. Since the flag has been enabled for a while
now, we can delete the flag and default to the enabled state.
We cannot remove the old code because we are still dependent on the
minimum git version supporting --batch-command
, which is scheduled to
land in git 2.42.0.
Closes #4573 (closed)