ui: tune badge styling a bit

ui: tune badge styling a bit

the idea is to blend in when no task is running, thus no
background-color there. When tasks are running use the proxmox
branding guideline dark-grey, it isn't used as often so it should
fall into ones eye when changing but it has some use so it doesn't
seems out of place.

Reduce the border radius by a lot, so that it seems similar to the
one our ExtJS theme uses for the buttons outside - the original
border radius seems like it comes from the time where this was
intended to be a floating badge, there it'd make sense but as
integrated button one this seems to fit the style much more.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>