Run memory monitoring inside AP tests with prmon

I use prmon from lb-conda DPA/analysis-productions

Tried to follow asyncio-ness as in the rest of the script.

The task is started after launching the test process, assuming that the gaudi process is a child process of the dirac command used to launch the test, prmon should track everything.

The monitor task should complete by itself once the process being monitored quits, but there is some stuff added to attempt to clean up if not. Two output files are produced that are uploaded to S3: prmon.json (summary stats) and prmon.txt (evolution of various metrics versus time). These can be used to produce bokeh plots and display on LbAPWeb.

Example prmon.txt

Time    wtime   pss     rss     swap    vmem    rchar   read_bytes      wchar   write_bytes     rx_bytes        rx_packets      tx_bytes        tx_packets      stime   utime   nprocs  nthreads
1661454549      24      103     612     0       108064  2012    0       0       0       10208   114     1295    8       0       0       1       1
1661454580      55      103     612     0       108064  2012    0       0       0       2484932 8221    7763101 5861    0       0       1       1
1661454611      86      103     612     0       108064  2012    0       0       0       3376696 14322   8557961 7767    0       0       1       1
1661454642      117     103     612     0       108064  2012    0       0       0       4884905 21695   10314346        10806   0       0       1       1

prmon is configured to sample the memory stats from the tracked process every 30 seconds (that's the default)

Not tested yet

Relates to https://gitlab.cern.ch/lhcb-dpa/project/-/issues/76 and #24 (closed)