Add '-nginx-election' suffix to NGINX ConfigMap

What does this MR do?

Add '-nginx-election' suffix to NGINX ConfigMap

Adds a suffix to the NGINX ElectionID ConfigMap to better clarify
the ConfigMap's purpose.

Originally discovered during development in
https://gitlab.com/gitlab-org/charts/gitlab/-/merge_requests/3091,
where we didn't initially know the source for the ConfigMap whose name
was simply the same as the Chart's release name.

Note: this change is specific to CI - it adjusts the helm install arguments passed to the NGINX Ingress Chart, telling it to add a suffix to the ConfigMap name used for NGINX's leader election.

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Testing

Confirmed that value was set in release:

$ helm get values rvw-ci-rename-nginx-election-c | yq '.nginx-ingress.controller.electionID'
rvw-ci-rename-nginx-election-c-nginx-election

Confirmed that ConfigMap existed:

$ k get cm rvw-ci-rename-nginx-election-c-nginx-election
NAME                                            DATA   AGE
rvw-ci-rename-nginx-election-c-nginx-election   0      131m

Confirmed that ConfigMap without the new suffix did not exist:

$ k get cm rvw-ci-rename-nginx-election-c
Error from server (NotFound): configmaps "rvw-ci-rename-nginx-election-c" not found

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.