[backport#16361] Remove redundant pre-TopUpKeypool check

Summary:
96b6dd468a4cb6077d1a2267d620d99d39aac7d0 Remove redundant pre-TopUpKeypool checks (Gregory Sanders)

Pull request description:

TopUpKeypool already has a quick check for `IsLocked()`

https://github.com/bitcoin/bitcoin/pull/16361/commits/96b6dd468a4cb6077d1a2267d620d99d39aac7d0

Backport of Core PR16361

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D7000