obs-ffmpeg: Remove forced x264 and aac for RTMP

Remove code forcing x264 and ffmpeg aac encoder. People using custom
ffmpeg output should be able to use other video and audio encoders when
streaming with RTMP, given its h264 or aac.

(cherry picked from commit 1166e504bbde35e4574af2cf6fb8104bcf96e088)

plugins/obs-ffmpeg/obs-ffmpeg-output.c

@@ -640,9 +640,7 @@ bool ffmpeg_data_init(struct ffmpeg_data *data, struct ffmpeg_cfg *config)
 	}
 #else
 	if (is_rtmp) {
-		data->config.audio_encoder = "aac";
 		data->config.audio_encoder_id = AV_CODEC_ID_AAC;
-		data->config.video_encoder = "libx264";
 		data->config.video_encoder_id = AV_CODEC_ID_H264;
 	}
 #endif