feat: (IAC-1044) update ingress-nginx default to v1.8.1

[dhoucgitter]

Changes

• Update the default Ingress-nginx chartVersion used to v4.7.1, and appVersion used to v1.8.1 for kubernetes cluster versions 1.24 or later
• Update CONFIG-VARS.md to indicate that the default INGRESS_NGINX_CHART_VERSION is 4.7.1 for kubernetes clusters whose version is >= 1.24

Tests

Scenario	Provider	kubernetes_version	ingress-NGINX version	ingress-nginx helm chart version	order	cadence	notes
1	Azure	1.26 (v1.26.6)	1.8.1	4.7.1	**	**	DAC ansible, deploy cmd: successful baseline,viya install, all pods stabilized, successful viya_admin login to Viya application
2	Azure	1.25 (v1.25.11)	1.8.1	4.7.1	n/a	n/a	DAC ansible, baseline install results: ingress-nginx-controller v1.8.1 at helm chart v4.7.1 is installed, see 1044-scenario.md file for k8s 1.25 console output
3	Azure	1.27 (v1.27.3)	1.8.1	4.7.1	n/a	n/a	DAC ansible, baseline install results: ingress-nginx-controller v1.8.1 at helm chart v4.7.1 is installed, see 1044-scenario.md file for k8s 1.27 console output
4	AWS	1.25 (v1.25.12-eks)	1.8.1	4.7.1	n/a	n/a	DAC ansible, baseline install results: ingress-nginx-controller v1.8.1 at helm chart v4.7.1 is installed, see 1044-scenario.md file for console output
5	Azure	1.24 (v1.24.15)	1.8.1	4.7.1	n/a	n/a	DAC ansible, baseline install results: ingress-nginx-controller v1.8.1 at helm chart v4.7.1 is installed, see 1044-scenario.md file for console output