[AAPM] DisallowInstallUnknownSources: remove set state after disable

After AAPM is disabled, all disallow install unknown sources toggles
should now go back to their original state, hence this change removes
the code that set them to MODE_ERRORED.

Bug: 369361373
Test: manually enabled, disabled, and observed the toggle is enabled
Test: atest DisallowInstallUnknownSourcesTest
Flag: android.security.aapm_feature_disable_install_unknown_sources
Change-Id: Id786f0e5026302cb3ef455b096e6007671db1668