Backport Core PR12246

Summary:

• configure: Make it possible to build only one of bitcoin-cli or bitcoin-tx
• Bugfix: Only run bitcoin-tx tests when bitcoin-tx is enabled

This is a backport of Core PR12246

Test Plan:
Build with autotool and ninja

Ran ninja check-all to make sure that the change in autotool didn't mess up the ninja integration test suite.

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5749