Make monitoring logs optional

Summary

I just noticed that the monitoring suite writes every 10 measurements (~9 seconds) the monitorables into a log file in /var/log/gemdaq (hard-coded). The feature cannot be disabled, but works only if the user has the proper permissions to the folder (on gem904daq04 it means being in the gempro group).

See the corresponding extract in the code.

What is the expected correct behavior?

Such a feature should be at most optional with a way to configure the output directory (e.g. with a xDAQ configuration parameter). Once the monitoring database will be implemented, a text dump can be removed; it the meantime it could be interesting for post-mortem analysis.

Relevant logs and/or screenshots

Log files are created unnoticed:

[lpetre@gem904daq04 cmsgemos]$ ls /var/log/gemdaq/* | wc -l
5481