Revise stable tag env strategy

[zaharidichev]

Currently, the publish workflow tries to crawl the github releases api in order to obtain the latest stable. This is causing problems for our Linkerd CI pipeline because the latest released stable is quite far back in the list (more than the default 30 items returned).

I have bumped the returned items params on the API request, but this is only a temporary solution. One option is to hardcode the latest stable that has been released as presumably it would not change.

For context:
#1842
https://github.com/linkerd/website/actions/runs/10826561944/job/30037781523