Revert "fix infinite recursion loop in SendGridInstantMessageViaXMLRPCAsync()"

There is a problem here with infinite recursion, but this patch loses the 'hunting' behaviour where the code will attempt multiple lookups if the avatar is teleporting rapidly around different simulators.
This patch only does a single lookup before giving up.

This reverts commit cecb446e0e91ede0b05ea9cf40c1313782241f3d.