Recover from app-op corruption bug.

We had been using OP_LEGACY_STORAGE as a signal that a package had
been installed before isolated storage had been enabled on the
device, but a recent regression lost all those values.

Thus, this logic attempts to recover that by saying: if no apps on
the device currently hold OP_LEGACY_STORAGE, and apps had been
installed or updated before the feature flag was enabled, then
grant the op to any apps installed before the flag was enabled.

Bug: 128872367, 128914416
Test: manual
Change-Id: I36fc9d6a5d4b48abb41f985208d3b286781d63dd