Improve PID file error handling
Summary:
- Improve PID file removing errors logging
- Make PID file creating errors fatal
- Move all PID file stuff to init.cpp
It is only used from init.cpp.
Move-only refactoring.
This is a backport of Core PR15278
The linter was skipped because we don't have that linter.
Test Plan:
ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D5775