[gstreamer,gst-rtsp-server] Update to 1.28.4

[ajtribick]

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version, or no changes were necessary.
• Any fixed CI baseline and CI feature baseline entries are removed from that file, or no entries needed to be changed.
• All patch files in the port are applied and succeed.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Exactly one version is added in each modified versions file.

Earlier attempt: #52375

This time I fully delete the moltenvk subproject to avoid Meson's auto-fallback, this should cause the MacOS CI to fail for gstreamer[core,vulkan] at the configuration stage. A build that fails at the stage of checking the .pc file for absolute paths is not the expected result here.

[BillyONeal]

Thank you! Can you fix the line endings in portfile.cmake to be LF by merging ajtribick#2 ?