cmd/coordinator/internal/legacydash: use built-in max/min to simplify the code

Change-Id: I0e2955f53c66225d8ead03f13faf2b6763cfadba
Reviewed-on: https://go-review.googlesource.com/c/build/+/664835
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/cmd/coordinator/internal/legacydash/build.go b/cmd/coordinator/internal/legacydash/build.go
index 605f163..3b68c41 100644
--- a/cmd/coordinator/internal/legacydash/build.go
+++ b/cmd/coordinator/internal/legacydash/build.go
@@ -218,13 +218,6 @@
 	return s[len(s)-l:]
 }
 
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 // Result returns the build Result for this Commit for the given builder/goHash.
 //
 // For the main Go repo, goHash is the empty string.