Fixes #3840: v1.7.3 is broken for direct launch

Fix direct launch with two changes:

1. ensure we store our own values locally as some BTLs want to look it up instead of just using their own internal cache. This is a partial commit of r29405 - the rest will come over in a later CMR.

2. remove a "shadow" variable in the pmi grpcomm module that caused us to lose the computed locality of our peers.