Activate LuCI, attendedsysupgrade and owut based on CONFIG_BUILDBOT

[Hauke Mehrtens]

Currently the LuCI integration into the builds is activated in the 
buildbot configuration. This configuration is not very publicly know. We 
already have the CONFIG_BUILDBOT which activates multiple settings 
needed for the buildbot builds which normal user builds normally do not 
need. I propose some changes to also use this to activate additional 
packages like LuCI, luci-app-attendedsysupgrade and owut.

With this change we will not include luci-app-attendedsysupgrade by 
default in normal user builds with LuCI any more.

This will activate LuCI also in buildbot builds from the main branch 
which is probably helpful anyway.

I would like to add this also to the 25.12 branch.

LuCI changes: https://github.com/openwrt/luci/pull/8303
Packages changes: https://github.com/openwrt/packages/pull/28512

I looked into this again because Paul started a discussion about this 
topic today.

Do We have more custom settings for buildbot builds?

Hauke