Steps to reproduce:
1. Open the attached project
2. Build and run to Android device
3. On device, open Settings -> Apps -> AssetBundleTest
4. Under the 'Storage' section, observe how much memory is used
5. Go back to Player
6. Press Download (to start downloading AB) and Cancel (to Abort the request)
7. Go back to Settings and notice that the amount of memory used has increased

Expected result: aborting webRequest should clean up the partly downloaded data
Actual result: repeating Download AB webRequest and aborting it will keep collecting partly downloaded data without any cleanup

Reproduced with: 2019.1.7f1, 2019.2.0b8, 2019.3.0a6
Unable to reproduce with older versions due to errors

Devices tested:
VLNQA00144, Samsung Galaxy S9 (SM-G960U1), Android 9, CPU: Snapdragon 845 SDM845, GPU: Adreno (TM) 630