[cmake] Fix dependencies for functional test targets

Summary: They are wrong :)

Test Plan:
On master:

ninja clean
ninja check-functional

Fails because bitcoin-wallet is not built.

With this patch:

ninja check-functional

Works.

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5763