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