Catch NPE when reportInstallationToSecurityLog

The scan result is null for installExistingPackageAsUser(), becuse
it is installing a package that already exists, there is no scanning
or parsing involved.

Like reportInstallationStats, we also catch the exception temporary
here. There is a follow up bug to handle it correctly.

Bug: 301397206
Test: manual.
Change-Id: Ie846264d2bc1cd300d67d5cf69e41b710716fa54