Fix ingress-nginx controller election (#10913)

Under the original code, leader election failed for ingress controllers
as a result of mismatch between election-id in the controller config,
and the resourceName in the relevant rule of role 'ingress-nginx'.
This appeared in the controller logs.

To fix the issue, a command-line option was added to container
execution (--election-id=...).

Now, the election-id agrees with the resourceName provided in
the role-ingress-nginx.yml file. A comment in that file was
changed to reflect the new logic.

Co-authored-by: Vasilis Samoladas <vsam@softnet.tuc.gr>
Co-authored-by: Mohamed Omar Zaian <mohamedzaian@gmail.com>