(PCP-428) define missing variable in restart_host_run_puppet test
(PCP-428) define missing variable in restart_host_run_puppet test

Last commit against this test, to fix some flakiness let a missing
variable definition squeak through, in the exception handling for
timeout.  This commit remedies this.

puppetlabs/pxp-agent,puppetlabs/pxp-agent,puppetlabs/pxp-agent