This commit does following changes to time variables in net_processing.h:
- Used {} initialization.
- Uses universal initializer auto.
- Uses chrono::literals
The reason for these changes is to make code simpler, and easier to
understand and rationalize.
This concludes backport of core#23832
https://github.com/bitcoin/bitcoin/pull/23832/commits/fe86eb50c986f7b5ccce63f984d8a51cd9ee9e2c
Depends on D13375