feat(helm): remove nginx configuration-snippet by default

[passionne]

Issue

https://gravitee.atlassian.net/browse/APIM-8630
https://gravitee.atlassian.net/browse/TT-6449

Description

By default, the console, portal and the management ingress
define this nginx configuration:

nginx.ingress.kubernetes.io/configuration-snippet: "etag on;\nproxy_pass_header ETag;\n"

However this configuration implies security issue
as mentioned in official documentation (CVE-2021-25742).
https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/annotations/#configuration-snippet

Also, this Etag configuration is not needed
for Console and Portal as the Etag are already
covered by the nginx in their respective container
to serve static files.

Finally, for the management-api it may not be needed.
So we keep it in comment to mention that it is still an option.

So the goal here is to remove the
nginx.ingress.kubernetes.io/configuration-snippet in helm/values.yaml.

For testing, deploy you APIM and then curl console and portal:

With Etag provided by nginx ingress:

curl -I -u 'admin:admin' 'https://your.management-api.url.gravitee.dev/management/v2/environments/DEFAULT/apis/f415bb33-9282-4f7f-95bb-3392821f7f97'
HTTP/2 200
etag: "1739439486097"

curl -I 'https://your.console.url.gravitee.dev/webcomponents/webcomponents-loader.js'
HTTP/2 200
etag: "67adbfd2-1e5d"

curl -I 'https://your.portal.url.gravitee.dev/webcomponents/webcomponents-loader.js'
HTTP/2 200
etag: "67adbfd0-1911"

Without Etag from nginx but Etag from management, console or portal
itself:

curl -I -u 'admin:admin' 'https://your.management-api.url.gravitee.dev/management/v2/environments/DEFAULT/apis/f415bb33-9282-4f7f-95bb-3392821f7f97'
HTTP/2 200
etag: "1739439486097"

curl -I 'https://your.console.url.gravitee.dev/webcomponents/webcomponents-loader.js'
HTTP/2 200
etag: "67ad234b-1911"

curl -I 'https://your.portal.url.gravitee.dev/webcomponents/webcomponents-loader.js'
HTTP/2 200
etag: "67ad2357-1e5d"

With both kind of nginx configuration to see ETag headers.