* optimizer: simplify GROUP and LOCAL to have one of each
Now that tensor cores only use LASTLOCAL, we can simplify to use
only that op everywhere.
The only use of GROUP is in matvec hand-coded opts and it doesn't
make a performance difference so switching to use only the top
behavior.
Also adds additional asserts to prevent tensor core dims from
being altered which causes bad kernels to be generated.
* search: remove duplicated actions