Remove 'additional_jar_files' on 'robolectric_binary' build target.

This is to fix the Chromium roll into WebRTC which breaks because of https://chromium-review.googlesource.com/c/chromium/src/+/6444145.

These 'additional_jar_files' were added with https://webrtc-review.googlesource.com/c/src/+/166603 but it seems to work fine without them now.

failing bot:
https://ci.chromium.org/ui/p/webrtc/builders/try/android_arm64_rel/82359/overview

Bug: None
Change-Id: Ifb9e50d82e2fa56a96c325ebe0dfe3f85f410084
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/387900
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#44431}