Binding on-demand #2: PerformFullTransportBackupTask usage

Migrate the full-backup task to use binding on-demand

Ref: http://go/br-binding-on-demand
Bug: 17140907
Test: make RunFrameworksServicesRoboTests
Test: runtest -p com.android.server.backup frameworks-services
Test: adb shell bmgr backupnow <packages>
      With transports manually unbound and also canceled the operation a
      few times. Then inspected TransportClient logcat
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: Manually unbound before GTS/CTS above.

Change-Id: I15abe970db0b9858e0e2e4eb666358db3a9d50ad