Make test_show_host_detail work with multi host installation

Get the host detail only if the host is compute host
and run the tests for all the compute host not just
for the first one.

Change-Id: I1830e6071c09d1e751048d74bd828d0eeac282f8
Closes-Bug: #1230000
Merge "Make test_show_host_detail work with multi host installation"