Unnecessary now that wcar is back to normal.

This reverts commit 8352a858db6b5937a1ae1a8f5762f795b85815e1.
Revert "On transaction failure, atomic now throws RedisTransactionException,"
will change this to to ex-info.

This reverts commit 312b86e32b7a3235f1ea36b7137c430cde324d0d.
Revert "Nested wcars use the same connection."
Not necessary, since we can use with-replies*

This reverts commit 32b8876807c2849b0be400b6a569e4330a303d07.