[backport#16366] init: Use InitError for all errors in bitcoind/qt

Summary:
Pull Request#16366

fa6f402bde146f92ed131e0c9c8e15a55e723307 Call node->initError instead of InitError from GUI code (Russell Yanofsky)
fad2502240a1c440ef03ac3f880475702e418275 init: Use InitError for all errors in bitcoind/qt (MarcoFalke)

Description:

Using the same InitError for startup error in the daemon and the gui makes it possible to run the tests with the gui again: (N.f.B: Depends on D5794)

sh
BITCOIND=bitcoin-qt ./test/functional/test_runner.py feature_includeconf feature_config_args

Pull Request#15864

ffea41f5301d5582665cf10ba5c2b9547a1443de Enable all tests in feature_config_args.py (Hennadii Stepanov)

Description:

Fix broken feature_config_args.py tests (disabled by MarcoFalke@fabe28a0cdcfa13e0e595a0905e3642a960d3077). All test are enabled now.

This is a backport of Core PR16366 with a partial backport of core PR15864

Test Plan:

ninja check check-functional

Reviewers: deadalnix, #bitcoin_abc

Reviewed By: deadalnix, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D5807