chore(internal/stategen): fix cleanup.go for special-case cloudtasks module (googleapis#13045)

Discover correct `../tasks/..` Go importpath from existing configuration
in a generalized solution for all modules.

Author: quartzmo

internal/stategen/cleanup.go

@@ -238,21 +238,48 @@ func cleanupOwlBotYaml(repoRoot, moduleName string) error {
 		return err
 	}
 
+	// Also check for a cleanup name, which may be different from the module name.
+	// For example, the cloudtasks module has the proto path .../cloud/tasks.
+	// We can derive this name from the postprocessor config.
+	ppc, err := loadPostProcessorConfig(filepath.Join(repoRoot, "internal/postprocessor/config.yaml"))
+	if err != nil {
+		return fmt.Errorf("loading postprocessor config: %w", err)
+	}
+	cleanupName := moduleName // Default to the module name.
+	importPrefix := "cloud.google.com/go/" + moduleName + "/"
+	for _, sc := range ppc.ServiceConfigs {
+		if strings.HasPrefix(sc.ImportPath, importPrefix) {
+			// The InputDirectory is the path to the API protos, relative to the
+			// googleapis root. It has a structure like:
+			// "google/cloud/service/v1" or "google/identity/accesscontextmanager/v1".
+			// The third component of this path is the service name as it appears
+			// in the `source:` lines of .OwlBot.yaml.
+			parts := strings.Split(sc.InputDirectory, "/")
+			if len(parts) > 2 {
+				cleanupName = parts[2]
+			}
+			// Assume the first service config for a module is sufficient to
+			// determine the cleanup name.
+			break
+		}
+	}
+
 	modulePathFragment := "/" + moduleName + "/"
+	cleanupPathFragment := "/" + cleanupName + "/"
 	lines := strings.Split(string(fileBytes), "\n")
 	var newLines []string
 	for i := 0; i < len(lines); i++ {
 		line := lines[i]
 		if strings.Contains(line, "source:") {
 			// It's a source line, check it for the module name.
-			if strings.Contains(line, modulePathFragment) {
+			if strings.Contains(line, modulePathFragment) || strings.Contains(line, cleanupPathFragment) {
 				if i+1 < len(lines) {
 					i++ // Remove both source and dest lines.
 				}
 				continue
 			}
 		}
-		if strings.Contains(line, modulePathFragment) {
+		if strings.Contains(line, modulePathFragment) || strings.Contains(line, cleanupPathFragment) {
 			// Remove any non-source line containing the module name.
 			continue
 		}

internal/stategen/cleanup_test.go

@@ -30,6 +30,7 @@ func TestCleanupLegacyConfigs(t *testing.T) {
 		"ai",
 		// Test an individually-released module in release-please-config-individual.json, etc.
 		"auth",
+		"cloudtasks",
 	}
 	for _, testModuleName := range testModuleNames {
 		// Create a temporary directory for the test repo.