Update interface quota on the handler

This avoids making expensive netd calls while holding the mRulesLock

Doesn't fix the problem of turning on hotspot while WiFi was connected.
It is no longer blocked on isNetworkMetered() call though.

Partial fix for following bugs...
Bug: 27857665
Bug: 28201280
Change-Id: I62f3c0b0571292cc1e156b48ce3329def41cdd07