fix: beta cleanup: remove deprecated classes and unused functionalities (#1300)

* fix: update code comment to reflect max size change

* fix: remove deprecated classes.

* fix integration test failures

* fix test failure

* .

* .

* .

Author: yirutang

google-cloud-bigquerystorage/clirr-ignored-differences.xml

@@ -16,4 +16,16 @@
     <className>com/google/cloud/bigquery/storage/v1beta2/JsonStreamWriter</className>
     <method>com.google.cloud.bigquery.storage.v1beta2.JsonStreamWriter$Builder newBuilder(java.lang.String, com.google.cloud.bigquery.Schema)</method>
   </difference>
+  <difference>
+    <differenceType>8001</differenceType>
+    <className>com/google/cloud/bigquery/storage/v1beta2/StreamWriter</className>
+  </difference>
+  <difference>
+    <differenceType>8001</differenceType>
+    <className>com/google/cloud/bigquery/storage/v1beta2/StreamWriter$Builder</className>
+   </difference>
+  <difference>
+    <differenceType>8001</differenceType>
+    <className>com/google/cloud/bigquery/storage/v1beta2/OnSchemaUpdateRunnable</className>
+   </difference>
 </differences>

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1beta2/JsonStreamWriter.java

@@ -116,23 +116,6 @@ public ApiFuture<AppendRowsResponse> append(JSONArray jsonArr, long offset) {
     }
   }
 
-  /**
-   * Refreshes connection for a JsonStreamWriter by first flushing all remaining rows, then
-   * recreates stream writer, and finally setting the descriptor. All of these actions need to be
-   * performed atomically to avoid having synchronization issues with append(). Flushing all rows
-   * first is necessary since if there are rows remaining when the connection refreshes, it will
-   * send out the old writer schema instead of the new one.
-   */
-  void refreshConnection()
-      throws IOException, InterruptedException, Descriptors.DescriptorValidationException {
-    synchronized (this) {
-      this.streamWriter.close();
-      this.streamWriter = streamWriterBuilder.build();
-      this.descriptor =
-          BQTableSchemaToProtoDescriptor.convertBQTableSchemaToProtoDescriptor(this.tableSchema);
-    }
-  }
-
   /**
    * Gets streamName
    *