Revert "priority compiles are proxyed to the priority servers"

This reverts commit 5375af085a1fc20def19a858e3f63c52f3bec9b0.
put the compile group on the session so proxied requests are sent to the correct place

I know this is premature optimisation however we do make a lot of requests
to the clsi for each compile and this will save mongo a lot of calls