[gstreamer]: fix pkgconfig parameters of gstreamer

[theartful]

I build gstreamer using vcpkg, and use these parameters to package my application. This fix correctly sets the values of the following parameters in pkgconfig file:

1. toolsdir
2. pluginscannerdir
3. pluginsdir

• 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
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[theartful]

@microsoft-github-policy-service agree