Drop unused init.h includes
Summary:
These were entirely unused, as based on successful compilation and a grep for: \bStartShutdown\(\)|\bShutdownRequested\(\)|\bInterrupt\(\)|\bShutdown\(\)|\bInitLogging\(\)|\bInitParameterInteraction\(\)|\bAppInitBasicSetup\(\)|\bAppInitParameterInteraction\(\)|\bAppInitSanityChecks\(\)|\bAppInitLockDataDirectory\(\)|\bAppInitMain\(\)|\bSetupServerArgs\(\)|\bLicenseInfo\(\)|g_wallet_init_interface|init.h
Partial backport of core PR13235 (commit e62fdfe):
https://github.com/bitcoin/bitcoin/pull/13235/commits/e62fdfeeab13ff65bcedac30f08a3216f3b29255
Test Plan: Build with both autotools and cmake.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D4464