Revert "Fix IERS_Auto logic now that IERS-A is bundled" - #16695

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I'm seeing some surprising (and seemingly related) errors within allowed_failures. I can't take another look before tommorow so please make sure you understand what's happening there if you're going to merge this.
Let me also ping @ayshih for visibility.

I don't understand the failures here, so I'm hoping that a server just happened to be down at the time of the CI runs. This reversion PR should be mooted by the fixes in #16697

Thanks! I would prefer #16697 but let's see how the CI fares over there first.

Yes this one iss definitely not more than a plan B, thanks @ayshih for coming up with an actual fix !