Cleanup some problems in new Perl test code

Noted by Tom Lane:
- PostgresNode had a BEGIN block which created files, contrary to
  perlmod suggestions to do that only on INIT blocks.
- Assign ports randomly rather than starting from 90600.

Noted by Noah Misch:
- Change use of no-longer-set PGPORT environment variable to $node->port
- Don't start a server in pg_controldata test
- PostgresNode was reading the PID file incorrectly; test the right
  thing, and chomp the line we read from the PID file.
- Remove an unused $devnull variable
- Use 'pg_ctl kill' instead of "kill" directly, for Windos portability.
- Make server log names more informative.

Author: Michael Paquier

src/bin/pg_basebackup/t/010_pg_basebackup.pl

@@ -168,13 +168,14 @@ my $recovery_conf = slurp_file "$tempdir/backupR/recovery.conf";
 
 # using a character class for the final "'" here works around an apparent
 # bug in several version of the Msys DTK perl
+my $port = $node->port;
 like(
 	$recovery_conf,
 	qr/^standby_mode = 'on[']$/m,
 	'recovery.conf sets standby_mode');
 like(
 	$recovery_conf,
-	qr/^primary_conninfo = '.*port=$ENV{PGPORT}.*'$/m,
+	qr/^primary_conninfo = '.*port=$port.*'$/m,
 	'recovery.conf sets primary_conninfo');
 
 $node->command_ok(