ext4: remove unused ext4_allocation_context::ac_groups_considered

Remove unused ext4_allocation_context::ac_groups_considered

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240105092102.496631-5-shikemeng@huaweicloud.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>