Description of problem:
There is a scenario where Satellite shows some errata as installable, despite Content Host has nothing to update. See particular scenario in reproducer.

Version-Release number of selected component (if applicable):
Sat 6.12 or anything newer.

How reproducible:
100%

Steps to Reproduce:
1. Sync RHEL8 BaseOS and AppStream and codeready-builder-for-rhel-8-x86_64-rpms repos.
2. Have CV with the three repos and with exclude filter "exclude errata issued after 2023-07-01" applied just to RHEL8 BaseOS and Appstream repos.
That means, RHSA-2023:4517 errata is filtered out as issued on 2023-08-08.
3. Have a Content Host with kernel-tools-libs-4.18.0-477.15.1.el8_8.x86_64 and same kernel installed, BUT not installed kernel-tools-libs-devel package.
4. Assign the Host to the CV.
5. run "dnf update" to ensure the Host can't get any update.
6. Check errata applicability for the Host.

(it is bit artificial reproducer, coming from a real user scenario:

• have CV with RHEL8 repos, published+promoted months ago (before the errata went out)
• have another CV just with CodeReady, up to date
• have CCV combining those CVs
  )

Actual results:
6. shows RHSA-2023:4517 errata as installable, despite "dnf update" shows nothing.

Expected results:
6. No errata shown as installable.

Additional info:
I think the problem with calculation comes from the fact, that:

• RHSA-2023:4517 contains many packages filtered out from the RHEL8 repos, but also package kernel-tools-libs-devel-4.18.0-477.21.1.el8_8.x86_64 from CodeReady repo (that is present in the CV)
• kernel-tools-libs package has an applicable update (via that errata), but not installable
• due to some confusion, katello thinks it is also installable de to the -devel package - despite the package is not present on the system..?

DEV Tracker for https://issues.redhat.com/browse/SAT-23088
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2262976