Remove unnecessary read in test

The test overrides the TestUploadDataProvider's read method, but then
adds a read to the dataProvider, which is redundant and confusing.

Change-Id: I747f6637dfc6f729278950daa93f1052075c1523
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1753591Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Commit-Queue: Benjamin Kirchman <kirchman@google.com>
Cr-Commit-Position: refs/heads/master@{#687322}

components/cronet/android/test/javatests/src/org/chromium/net/CronetUrlRequestTest.java

@@ -1391,7 +1391,6 @@ public class CronetUrlRequestTest {
                 uploadDataSink.onReadSucceeded(false);
             }
         };
-        dataProvider.addRead("test".getBytes());
         builder.setUploadDataProvider(dataProvider, callback.getExecutor());
         builder.addHeader("Content-Type", "useless/string");
         builder.build().start();