simple-init: add configurable RA timeout with network-manager
This is a follow-on to I475a253091cbaf63687b91c748c31a6753bb0f57 as we
are still seeing issues on some clouds with unconfigured networking.
We increase the timeout, but also make it configurable so we can
fiddle it without a dib release in the gate.
To follow-on from the experimentation done by clarkb, I can confirm by
emperical testing on a Centos 7 image (from today, today being this
change's date) that setting
by itself is "fatal" and the interfaces do not come up; i.e. nm does
not by default seem to re-enable ipv6 for the interface. However,
to the interface file *does* seem to make it work, even if
"all.autoconf=0" is set (then again, there's also bugs about the
effect of this ). However, no extant distribution (I can currently
find) does anything like this by default.
If this continues, this may be an option. Another might be to avoid
the use of the nm-settings-ifcfg-rh profiles and move directly to nm
ini files with glean.