bcr_compatibility: Allow skipping waiting for approval (#2084)

diff --git a/buildkite/bazel-central-registry/bcr_compatibility.py b/buildkite/bazel-central-registry/bcr_compatibility.py
index a3397d3..2c8253d 100644
--- a/buildkite/bazel-central-registry/bcr_compatibility.py
+++ b/buildkite/bazel-central-registry/bcr_compatibility.py
@@ -116,19 +116,15 @@
     # Respect USE_BAZEL_VERSION to override bazel version in presubmit.yml files.
     bazel_version = os.environ.get("USE_BAZEL_VERSION")
     for module_name, module_version in modules:
-        previous_size = len(pipeline_steps)
-
         configs = bcr_presubmit.get_anonymous_module_task_config(module_name, module_version, bazel_version)
         bcr_presubmit.add_presubmit_jobs(module_name, module_version, configs.get("tasks", {}), pipeline_steps, overwrite_bazel_version=bazel_version, calc_concurrency=calc_concurrency)
         configs = bcr_presubmit.get_test_module_task_config(module_name, module_version, bazel_version)
         bcr_presubmit.add_presubmit_jobs(module_name, module_version, configs.get("tasks", {}), pipeline_steps, is_test_module=True, overwrite_bazel_version=bazel_version, calc_concurrency=calc_concurrency)
 
-        if len(pipeline_steps) == previous_size:
-            bcr_presubmit.error("No pipeline steps generated for %s@%s. Please check the configuration." % (module_name, module_version))
-
     if pipeline_steps:
-        # Always wait for approval to proceed
-        pipeline_steps = [{"block": "Please review generated jobs before proceeding", "blocked_state": "running"}] + pipeline_steps
+        if not "SKIP_WAIT_FOR_APPROVAL" in os.environ:
+            # Wait for approval to proceed
+            pipeline_steps.insert(0, {"block": "Please review generated jobs before proceeding", "blocked_state": "running"})
         if bazelci.use_bazelisk_migrate():
             pipeline_steps += create_step_for_report_flags_results()