Revert "gstvalue: Avoid expensive fallback on intersection"

Revert "gstvalue: Avoid expensive fallback on intersection"

This reverts commit cd751c2de39969ab6187eab12e4e8a85e0467cf7.
Reverts https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/406

Fixes glviewconvert negotiation in e.g.:

gltestsrc ! glviewconvert output-mode-override=side-by-side ! glstereosplit name=s s.left ! queue ! fakesink s.right ! queue ! glimagesink

Problem here is that intersecting flagsets in gst_value_intersect will
always find a value comparison function but may fail a direct type
comparison due to flagsets supporting derived types.  When flagset
derived types are intersected, an intersection will therefore always
fail.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/441>