It's not used anymore because it does work so well.
The problem is that while it transparently proxies param enums on
ports to peers, it fails to emit events when those peer
params change in a way that would make the enum result change as well.
This makes it quite hard to use this correctly.
Move the spa tests to the pwtest framework. The pod tests have only been
wrapped in the function callers, they don't use the variuos pwtest helpers -
too much work for very little gain here. Can be done incrementally if needed.
Note that this removes the spa tests from the installed tests. Arguably,
installing those tests was unnecessary anyway since they are static binaries
and don't load anything. So having them installed runs the same tests as
having them run in the source tree.
Goal for the pwtest framework is to allow for installed tests, just not there
yet.
