remove unused NR RRC code

changed milestone to %REVIEW_CAN_START

added 5G-NR label

requested review from @mirazabal

OAI RAN-CI-develop build (4562): passed (https://open5glab.eurecom.fr:8083/jenkins/job/RAN-CI-develop/4562/)

Looks good for me, @mirazabal please check and set the milestone accordingly

OAI RAN-Container-Parent build (3161): failed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/3161/)

changed milestone to %REVIEW_COMPLETED_AND_APPROVED

If it passes the CI OK.

changed milestone to %OK_TO_BE_MERGED

resolved all threads

mentioned in merge request !1800 (merged)

mentioned in commit 0cacf29d

merged