feat(publick8s) fine tune ingress rule for updates.jenkins.io

[dduportal]

Related to jenkins-infra/helpdesk#2649 (comment)

This PR fine tune the ingress rule of update.jenkins.io to only send requests ending with .json, .html or .txt extensions to mirrorbits:

• The https://updates.jenkins.io/ URL will still be sent to Apache (which has all the files) so it can serve the index.html file as the default file before trying listing diretctories
• All other html and txt files are copied to the mirror along the json files (both UC and crawler)

[dduportal]

helmfil diff says:

updates-jenkins-io, updates-jenkins-io-mirrorbits-parent, Ingress (networking.k8s.io) has changed:
...
                  port:
                    number: 80
-           - path: /.*[.](deb|hpi|war|rpm|msi|pkg|sha256|md5sum|zip|gz|pdf|json|svg|sh|jpeg|ico|png|html|txt)$
+           - path: /.*[.](json|html|txt)$
              pathType: ImplementationSpecific
              backend:
...

let's roll