feat: Add automap_substitutions flag to use substitutions as envs in …

…Cloud Build

PiperOrigin-RevId: 551218480

google/devtools/cloudbuild/v1/cloudbuild.proto

@@ -802,6 +802,11 @@ message BuildStep {
   //
   // When script is provided, the user cannot specify the entrypoint or args.
   string script = 19;
+
+  // Option to include built-in and custom substitutions as env variables
+  // for this build step. This option will override the global option
+  // in BuildOption.
+  optional bool automap_substitutions = 20;
 }
 
 // Volume describes a Docker container volume which is mounted into build steps
@@ -2245,6 +2250,10 @@ message BuildOptions {
   // overridden in the build configuration file.
   bool dynamic_substitutions = 17;
 
+  // Option to include built-in and custom substitutions as env variables
+  // for all build steps.
+  bool automap_substitutions = 22;
+
   // Option to define build log streaming behavior to Cloud
   // Storage.
   LogStreamingOption log_streaming_option = 5;