Add more logging to new 028_pitr_timelines.pl test.
The test has failed a couple of times on buildfarm member 'hoverfly'. It
gets stuck waiting for the standby to archive
000000020000000000000003
WAL segment. I don't understand why, but with DEBUG1, we will get messages
in the log whenever a segment is archived, which hopefully will give a
clue the next time it happens.