Adds an ability to generate network boot templates even for nodes that
use local boot via the new ``[pxe]enable_netboot_fallback`` option.
This is required to work around the situation when switching boot devices
does not work reliably.
Depends-On: https://review.opendev.org/#/c/736191/
Change-Id: Id80f2d88f9c92ff102340309a526a9b3992c6038
Story: #2007610
Task: #39600