Printed events processed interval does not correspond to real processing time

[ppcad]

Logprep can print the number of processed events for a configured interval.
However, the printed interval is smaller than the actual processing time if processing one event takes longer than that interval.
This can happen when Logprep is starting if it has to load a lot of rules and the print interval is smaller than the time it takes to load them.

Expected behavior
The printed interval for processed events corresponds to the real processing time.

Current behavior
The printed interval for processed can be smaller the real processing time.

Steps to reproduce
Set a small "print_processed_period" and load a lot of rules.

Environment

Logprep version: latest
Python version: 3.11

Possible solution
This might be solved in multiple ways:

1. Print the real time it took instead of the configured interval time. This means the printed interval might increase if it took longer than configured.
2. Ensure the processed count gets always printed at the interval, even if events are still being processed.
3. Ensure everything is loaded before the counting starts.

[dtrai2]

I just opened a pull request, maybe you can check if that solves the issue.