init: Factor out AppInitLockDataDirectory

Summary:
Alternative to #10818, alternative solution to #10815.

After this change: All the AppInit steps before and inclusive
AppInitLockDataDirectory must not have Shutdown() called in case of
failure. Only when AppInitMain fails, Shutdown should be called.

Changes the GUI and bitcoind code to consistently do this.

Backport of Core PR 10832.
Completes T426

Co-authored-by: Jason B. Cox <contact@jasonbcox.com>

Test Plan: ninja && test_runner.py

Reviewers: deadalnix, schancel, #bitcoin_abc

Reviewed By: deadalnix, #bitcoin_abc

Subscribers: teamcity

Differential Revision: https://reviews.bitcoinabc.org/D1928