Android JNI generation: Set JNI namespace in build files

This CL removes the use of the @JNINamespace annotation and instead
sets the correct JNI namespace in the build file.

Bug: webrtc:8278
Change-Id: Ia4490399e45a97d56b02c260fd80df4edfa092bf
Reviewed-on: https://webrtc-review.googlesource.com/76440
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23299}

sdk/android/api/org/webrtc/HardwareVideoEncoderFactory.java

@@ -26,7 +26,6 @@ import javax.annotation.Nullable;
 
 /** Factory for android hardware video encoders. */
 @SuppressWarnings("deprecation") // API 16 requires the use of deprecated methods.
-@JNINamespace("webrtc::jni")
 public class HardwareVideoEncoderFactory implements VideoEncoderFactory {
   private static final String TAG = "HardwareVideoEncoderFactory";