Add e2e test for rewrite-target annotation kube-lego failure

[zrdaley]

What this PR does / why we need it:
This PR adds and e2e-test for the edge case that currently breaks kube-lego. This issue causes requests to the path /.well-known/acme/challenge to be redirected to the / path when the rewrite-target annotation is set for the index route.

This annotation enforces the use of the ~* location modifier. In NGINX, regex paths take priority over regular prefixes unless the = or ^~ location modifiers are used.

Which issue this PR fixes :
Partially fixes https://github.com/Shopify/edgescale/issues/659

Special notes for your reviewer:
Currently this test will fail. Additional changes need to be made to prevent this issue from occurring.

Relevant links:

• Ingress-Nginx Regex Support Project Brief
• Spreadsheet of regex support for ingress controllers
• Discussion of standardizing regex support among ingress controllers
• Open issue on lack of regex support in ingress-nginx
• NGINX location modifiers

@ElvinEfendi @sbfaulkner

[k8s-ci-robot]

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[zrdaley]

See: #3078