docs: remove per-version API tabs

[howardjohn]

Fixes #2994

[istio-policy-bot]

🤔 🐛 You appear to be fixing a bug in Go code, yet your PR doesn't include updates to any test files. Did you forget to add a test?

Courtesy of your friendly test nag.

[linsun]

LGTM

[ericvn]

One thing I want to investigate, which is likely a nit, is why the .html file is under an older version in the source tree (ex: networking/v1alpha3/service_entry.pb.html as opposed to being in v1beta1). I suspect we have logic to only create one in the older version (at least in the case of dupes). Overall, this doesn't make a change in what is shown in istio.io, it's just where the file is placed here.

[howardjohn]

One thing I want to investigate, which is likely a nit, is why the .html file is under an older version in the source tree (ex: networking/v1alpha3/service_entry.pb.html as opposed to being in v1beta1). I suspect we have logic to only create one in the older version (at least in the case of dupes). Overall, this doesn't make a change in what is shown in istio.io, it's just where the file is placed here.

v1beta1 ones have $mode: none to avoid generation to avoid duplicates