[backport#16911] wallet: Only check the hash of transactions loaded from disk

Summary:
Only check the hash of transactions loaded from disk (Andrew Chow)

Pull request description:

It feels unnecessary to do a full `CheckTransaction` for every transaction saved in the wallet. It should not be possible for an invalid transaction to get into the wallet in the first place, and if there is any disk corruption, the hash check will catch it.

Backport of Core PR16911

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7386