op-node/testlog: auto-adjust padding for test log alignment (#2928)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

op-node/testlog/testlog.go

@@ -135,17 +135,23 @@ func (l *logger) SetHandler(h log.Handler) {
 	l.l.SetHandler(h)
 }
 
+// tracks the largest seen decoration length, to make alignment between all test loggers consistent.
+var logDecorationLength = 12
+
 // flush writes all buffered messages and clears the buffer.
 func (l *logger) flush() {
 	l.t.Helper()
 	// 2 frame skip for flush() + public logger fn
 	decorationLen := estimateInfoLen(2)
-	padding := 20
-	if decorationLen <= 25 {
-		padding = 25 - decorationLen
+	if decorationLen > 30 { // limit to a maximum size, to avoid huge padding
+		decorationLen = 30
+	}
+	// logDecorationLength is only increasing, should be safe even with inaccurate concurrent use.
+	if decorationLen > logDecorationLength { // increase padding if we encounter larger decoration
+		logDecorationLength = decorationLen
 	}
 	for _, r := range l.h.buf {
-		l.t.Logf("%*s%s", padding, "", l.h.fmt.Format(r))
+		l.t.Logf("%*s%s", logDecorationLength-decorationLen, "", l.h.fmt.Format(r))
 	}
 	l.h.buf = nil
 }