Remove nitrogen from CI

Since zephyr testing has been enabled on qemu-x86 and qemu-cortex-m3 in the last iteration. it is ok to remove the nitrogen board from CI now.

CC @sradakovi

changed milestone to %goofy beta

added Doing goofybeta teamtesting labels

set weight to 1

assigned to @chaseqi

added to epic &153 (closed)

changed iteration to Oniro Core Iterations Sep 1, 2022 - Sep 30, 2022

mentioned in commit chaseqi/oniro@4c74fed9

mentioned in merge request !298 (merged)

mentioned in commit bc15a37c

closed with commit 4c74fed9

closed with merge request !298 (merged)

removed Doing label