tools/cts: Rekick cancelled or infra-failed builds

For commands like `cts update`, `cts export`:
If a build completed with `StatusInfraFailure` or `StatusCanceled` and we're trying to obtain the results, re-kick the build.

Bug: dawn:1342
Change-Id: I84565b06eb70e92f3b75a0ab2befd7ed83315140
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/92940
Auto-Submit: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>

tools/src/cmd/cts/common/build.go

@@ -137,9 +137,20 @@ func GetOrStartBuildsAndWait(
 		}
 	}
 
+	// Returns true if the build should be re-kicked
+	shouldKick := func(build buildbucket.Build) bool {
+		switch build.Status {
+		case buildbucket.StatusUnknown,
+			buildbucket.StatusInfraFailure,
+			buildbucket.StatusCanceled:
+			return true
+		}
+		return false
+	}
+
 	// Kick any missing builds
 	for name, builder := range cfg.Builders {
-		if _, existing := builds[name]; !existing {
+		if build, found := builds[name]; !found || shouldKick(build) {
 			build, err := bb.StartBuild(ctx, ps, builder, retest)
 			if err != nil {
 				return nil, err