Align log_line_prefix in CI and TAP tests with pg_regress.c

log_line_prefix is changed to include "%b", the backend type in the TAP
test configuration.  %v and %x are removed from the CI configuration,
with the format around %b changed.

The lack of backend type in postgresql.conf set by Cluster.pm for the
TAP test configuration was something that has been bugging me, beginning
the discussion that has led to this change.  The change in the CI has
come up during the discussion, to become consistent with pg_regress.c,
%v and %x not being that useful to have.

Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/aC0VaIWAXLgXcHVP@paquier.xyz

src/test/perl/PostgreSQL/Test/Cluster.pm

@@ -684,7 +684,7 @@ sub init
 	print $conf "\n# Added by PostgreSQL::Test::Cluster.pm\n";
 	print $conf "fsync = off\n";
 	print $conf "restart_after_crash = off\n";
-	print $conf "log_line_prefix = '%m [%p] %q%a '\n";
+	print $conf "log_line_prefix = '%m %b[%p] %q%a '\n";
 	print $conf "log_statement = all\n";
 	print $conf "log_replication_commands = on\n";
 	print $conf "wal_retrieve_retry_interval = '500ms'\n";

src/tools/ci/pg_ci_base.conf

@@ -10,5 +10,5 @@ log_autovacuum_min_duration = 0
 log_checkpoints = true
 log_connections = all
 log_disconnections = true
-log_line_prefix = '%m [%p][%b] %q[%a][%v:%x] '
+log_line_prefix = '%m %b[%p] %q%a '
 log_lock_waits = true