run `git cherry-pick --abort` and then clean up the branch

def abort_cherry_pick(self):
        """
        run `git cherry-pick --abort` and then clean up the branch
        """
        if self.initial_state != WORKFLOW_STATES.BACKPORT_PAUSED:
            raise ValueError("One can only abort a paused process.")

        cmd = ["git", "cherry-pick", "--abort"]
        try:
            set_state(WORKFLOW_STATES.ABORTING)
            self.run_cmd(cmd)
            set_state(WORKFLOW_STATES.ABORTED)
        except subprocess.CalledProcessError as cpe:
            click.echo(cpe.output)
            set_state(WORKFLOW_STATES.ABORTING_FAILED)
        # only delete backport branch created by cherry_picker.py
        if get_current_branch().startswith("backport-"):
            self.cleanup_branch(get_current_branch())

        reset_stored_config_ref()
        reset_state()