Binding on-demand #6: Transport attributes usage

Migrate the attribute queries from the Transport to the
TransportManager. Migrate all calls except currentDestinationString
because that's the one that changes and we should only migrate
after we have GMSCore that implements the push-from-transport
model.

Looking at method recordInitPendingLocked(), we only sent
MSG_RETRY_INIT if the transport threw while calling transportDirName
or the binder was null. With binding on-demand both of these cases
can't happen - i.e. we can't fail anymore. So, I removed the
message entirely.

Change-Id: I45a305704274c8b0c88637e3ccafc658639b2dfa
Ref: http://go/br-binding-on-demand
Bug: 17140907
Test: m -j RunFrameworksServicesRoboTests
Test: gts-tradefed run commandAndExit gts-dev -m GtsBackupTestCases
Test: gts-tradefed run commandAndExit gts-dev -m GtsBackupHostTestCases
Test: cts-tradefed run commandAndExit cts-dev -m CtsBackupTestCases
Test: runtest -p com.android.server.backup frameworks-services
Test: adb shell bmgr backupnow <packages>
Test: adb shell bmgr fullbackup <packages>
Test: adb shell cmd jobscheduler run -f android <job_id>
Test: adb shell bmgr enable false (being enabled before)
Test: adb shell dumpsys backup
Test: adb shell bmgr init <transport>
Test: Observed logs and used debugger to check proper code was being
Test: called in above commands