OpTestUtil: Trigger refresh of host login prompt
OpTestUtil: Trigger refresh of host login prompt

When logging into the host OS out-of-band (eg. IPMI) the login prompt
does not respond to Ctrl-L as expected. If we know we're waiting for a
host login prompt (eg. we know the state or we're booting up from
Petitboot), trigger a proper refresh by hitting enter at the prompt.

Signed-off-by: Samuel Mendoza-Jonas <f16bed56189e249fe4ca8ed10a1ecae60e8ceac0@mendozajonas.com>

open-power/op-test-framework,open-power/op-test-framework,open-power/op-test-framework