Remove agent version from cc-env output

[jodh-intel]

The Agent version field in the cc-env output...

$ cc-runtime cc-env|grep -A 2 Agent
[Agent]
  Type = "hyperstart"
  Version = "<<unknown>>"

... is always <<unknown>> as there is no clean way to query it.

This could be done using losetup + mount, but for now atleast we're putting that functionality into the collect script (see #1055).

Remove Agent.Version from the cc-env output as it serves no purpose.