[QA] Determine memory requirements for the antivirus service

[mmattel]

References: #6803 (antivirus seems to keep files in memory)

With the comment from @wkloucek, we should consider implementing an own QA to determine the memory requirements necessary for different cases and settings for the antivirus service.

Because AV is crucial in production, any service blockage is impacting negatively.

The information about antivirus memory requirements is important for devs and admins and heavily depends on settings of ANTIVIRUS_WORKERS, ANTIVIRUS_MAX_SCAN_SIZE and GOMEMLIMIT.

Quote

What I tried with ANTIVIRUS_WORKERS == 1:

-> 700M memory for 50MB file -> factor 14
-> 7000M memory for 844MB file -> factor 8,3

This means you probably need to set memory limit = max file size x workers x factor 8 - 14. Even though that also depends on the GOMEMLIMIT you set.

The above is just guesswork. If you want to document the product capabilities, I think this needs to be tested and not guessed.

@ScharfViktor @kobergj