Android: Showing duplicate node key after recent update
## The problem
Reported in Tailscale: Android: Showing duplicate node key after recent update.
## The fix
Android showing 'Duplicate Node key' in the admin console after updating: caused by the taildrop directory picker change in Tailscale 1.84. Fixed with the new behavior in 1.86, which no longer asks you to pick a taildrop directory until you need to receive a file with taildrop. Upgrade the Android app to >= 1.86. Maintainer-confirmed.