Fix external cache and secondary user bugs.

External cache files now have their own GID range, so measure using
those quotas.  Fix secondary user code measurement, since it always
lives under user 0.  Fix secondary user data measurement in manual
mode; we need to match based on appId instead of pure UID.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.StorageHostTest
Bug: 35812899, 35844919, 37193650
Change-Id: Ic3b153798164c33ea10e8a4dabc65edff26c56ca