Disable overlays while installer is resumed

The install button can be disabled for other reasons, hence we have to
store the enabled state independant of the resumed/paused state.

Test: gts-tradefed run gts-dev -m PackageInstallerTapjacking
Fixes: 62239598
Change-Id: I2effa0f5afacfaed217a030550a778e32912cfbb