Use ParcelFileDescriptor instead of FileDescriptor in the aidl

Using FileDescriptor in the aidl will refer to
Parcel.readRawFileDescriptor() and Parcel.writeRawFileDescriptor()
whilie trying to do parcel operations. Those two APIs are hidden
and not accessible for the incoming ConnectivityService mainline
module. For such use cases in a module, it should be replaced by
using ParcelFileDescriptor that is designed for such usages.

Bug: 170598012
Test: atest FrameworksNetTests CtsNetTestCasesLatestSdk
Change-Id: Ia7e3a71ccb4b136cc55c9e90a384870c32cfd37b