m/test/e2e: use concise-style logging

Making our test logs look like LogEntry.ConciseString() means we have
significantly more readable test logs.

Change-Id: I0b1eab6a5a837bb2001f3b32779c23df2feaa381
Reviewed-on: https://review.monogon.dev/c/monogon/+/1362
Reviewed-by: Leopold Schabel <leo@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/test/launch/cluster/prefixed_stdio.go b/metropolis/test/launch/cluster/prefixed_stdio.go
index 059c3cb..3ea3e18 100644
--- a/metropolis/test/launch/cluster/prefixed_stdio.go
+++ b/metropolis/test/launch/cluster/prefixed_stdio.go
@@ -22,7 +22,8 @@
 func newPrefixedStdio(num int) prefixedStdio {
 	return prefixedStdio{
 		logbuffer.NewLineBuffer(1024, func(l *logbuffer.Line) {
-			s := strings.TrimSpace(l.String())
+			s := strings.TrimRight(l.String(), " \t\n\r")
+			s = strings.TrimLeft(s, "\n\r\t")
 			// TODO(q3k): don't just skip lines containing escape sequences, strip the
 			// sequences out. Or stop parsing qemu logs and instead dial log endpoint in
 			// spawned nodes.