Labs: prevent ec2id fact from returing errors

If the curl to the master fails, return nothing rather than
the 500 body (which destroys the configuration); base will
check of that and fail rather than mangle puppet.conf

Bug: 63322
Change-Id: I24b80009aa54edfe3904e01b01800a5c62853e91
Merge "Labs: prevent ec2id fact from returing errors" into production