Use the v1 index.json for all templates not just v2

[nturinski]

Fixes #4646
Fixes #4599

[alexweininger]

Can you tl;dr this? For me and future us?

[nturinski]

Sure. Basically, at some point, the templates team stopped maintaining the v2 section of the templates feed for index-v2.json. Remember, templates were broken into v1 and v2 (though as far as I know, Python is the only runtime that uses v2. Typescript/Javascript programming model is still hard-coded.)

However, the decision to completely deprecate the index-v2.json was made a few weeks ago, so newer versions (I believe it's at 4.22.0 now) are not being added to the list which was causing the bug.

The templates team still maintains the old index.json where you have to build the urls yourself. I was already using it for the v2 templates, so now I'm just doing it for all the templates.