Ignore goroutines spanwned by log.init during leakcheck. (#1368)

Author: MakMukhi

Diff for: test/end2end_test.go

@@ -4240,6 +4240,7 @@ func interestingGoroutines() (gs []string) {
 			strings.Contains(stack, "runtime.goexit") ||
 			strings.Contains(stack, "created by runtime.gc") ||
 			strings.Contains(stack, "created by runtime/trace.Start") ||
+			strings.Contains(stack, "created by google3/base/go/log.init") ||
 			strings.Contains(stack, "interestingGoroutines") ||
 			strings.Contains(stack, "runtime.MHeap_Scavenger") ||
 			strings.Contains(stack, "signal.signal_recv") ||