log: allow tabs in log messages (#26630)

* log: allow tabs in log messages

This fixes a regression where panic reports in RPC handlers were quoted
because they contain tab characters.

* Update format.go

log/format.go

@@ -492,8 +492,8 @@ func escapeString(s string) string {
 func escapeMessage(s string) string {
 	needsQuoting := false
 	for _, r := range s {
-		// Carriage return and Line feed are ok
+		// Allow CR/LF/TAB. This is to make multi-line messages work.
-		if r == 0xa || r == 0xd {
+		if r == '\r' || r == '\n' || r == '\t' {
 			continue
 		}
 		// We quote everything below <space> (0x20) and above~ (0x7E),