crash when uploading 2500 images

### Steps to reproduce
1. create a folder with more than 2500 pictures on a lineage whyred phone
2. select to upload the pictures

### Expected behaviour
- the screen goes black (probably because the reading oft the folder takes too long)

### Actual behaviour
- after a while a crash report is shown

Device model:

************ CAUSE OF ERROR ************

```
java.util.concurrent.TimeoutException: com.android.internal.os.BinderInternal$GcWatcher.finalize() timed out after 10 seconds
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:422)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:188)
at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:209)
at java.lang.Daemons$FinalizerDaemon.runInternal(Daemons.java:232)
at java.lang.Daemons$Daemon.run(Daemons.java:103)
at java.lang.Thread.run(Thread.java:764)
```

************ APP INFORMATION ************
ID: com.nextcloud.android.beta
Version: 20200809
Build flavor: versionDev

************ DEVICE INFORMATION ************
Brand: Xiaomi
Device: whyred
Model: Redmi Note 5 Pro
Id: OPM6.171019.030.K1
Product: whyred

************ FIRMWARE ************
SDK: 27
Release: 8.1.0
Incremental: fc5e494154