Recover the `decreaseTimelock` case once it is fixed in CVL

eet() increases for `decreaseTimeLock` is a critical component of the overall proof and the most interesting case, which is currently skipped because of the certora bug. we can merge, but not sure how much value it adds without the decreaseTimeLock case. _Originally posted by @bhargavbh in https://github.com/morpho-org/vault-v2/pull/835#pullrequestreview-3688232056_