When boot is managed by the ironic side, a node is powered on
right after starting introspection. Inspector's own delays play
no role and may actually prevent introspectin from happening if
a node boots faster than it's whitelisted in the PXE filter.
This changes moves the delay handling later in the process and
only does it when manage_boot is True.
Change-Id: If7de8b66ea42eff2966c62a9a0529ab9a5c06f26
Story: #2007658
Task: #39745