test: coverage improvements in interface-bitcoin_cli.py

Summary:

• add coverage for bitcoin-cli -rpcwait
• verify bitcoin-cli -version with node stopped and improve/harmonize the test logging.
• verify cli.getwalletinfo in wallet section
• add -getinfo "unlocked_until" and "headers" coverage

This is a backport of Core PR18653

Test Plan: test/functional/test_runner.py interface_bitcoin*

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D8931