fix: migrate iam/admin/v1 to grpc_service_config

PiperOrigin-RevId: 317376637

google/iam/admin/v1/BUILD.bazel

@@ -62,6 +62,7 @@ java_gapic_library(
     name = "admin_java_gapic",
     src = ":admin_proto_with_info",
     gapic_yaml = "iam_gapic.yaml",
+    grpc_service_config = "iam_grpc_service_config.json",
     package = "google.iam.admin.v1",
     service_yaml = "iam.yaml",
     test_deps = [
@@ -188,6 +189,7 @@ py_gapic_library(
     name = "admin_py_gapic",
     src = ":admin_proto_with_info",
     gapic_yaml = "iam_gapic.yaml",
+    grpc_service_config = "iam_grpc_service_config.json",
     package = "google.iam.admin.v1",
     service_yaml = "iam.yaml",
     deps = [
@@ -232,6 +234,7 @@ php_gapic_library(
     name = "admin_php_gapic",
     src = ":admin_proto_with_info",
     gapic_yaml = "iam_gapic.yaml",
+    grpc_service_config = "iam_grpc_service_config.json",
     package = "google.iam.admin.v1",
     service_yaml = "iam.yaml",
     deps = [