replay: stop using `the_repository`

replay: stop using `the_repository`

In `create_commit()` we're using `the_repository` even though we already
have a repository passed to use as an argument. Fix this.

Note that we still cannot get rid of `USE_THE_REPOSITORY_VARIABLE`. This
is because we use `DEFAULT_ABBREV and `get_commit_output_encoding()`,
both of which are stored as global variables that can be modified via
the Git configuration.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>