build(bigquery/storage): Only generate gRPC clients for google/cloud/bigquery/storage/v1alpha

bigquery/storage/apiv1alpha/gapic_metadata.json

@@ -0,0 +1,43 @@
+{
+  "schema": "1.0",
+  "comment": "This file maps proto services/RPCs to the corresponding library clients/methods.",
+  "language": "go",
+  "protoPackage": "google.cloud.bigquery.storage.v1alpha",
+  "libraryPackage": "cloud.google.com/go/bigquery/storage/apiv1alpha",
+  "services": {
+    "MetastorePartitionService": {
+      "clients": {
+        "grpc": {
+          "libraryClient": "MetastorePartitionClient",
+          "rpcs": {
+            "BatchCreateMetastorePartitions": {
+              "methods": [
+                "BatchCreateMetastorePartitions"
+              ]
+            },
+            "BatchDeleteMetastorePartitions": {
+              "methods": [
+                "BatchDeleteMetastorePartitions"
+              ]
+            },
+            "BatchUpdateMetastorePartitions": {
+              "methods": [
+                "BatchUpdateMetastorePartitions"
+              ]
+            },
+            "ListMetastorePartitions": {
+              "methods": [
+                "ListMetastorePartitions"
+              ]
+            },
+            "StreamMetastorePartitions": {
+              "methods": [
+                "StreamMetastorePartitions"
+              ]
+            }
+          }
+        }
+      }
+    }
+  }
+}