Port #7770 fix to 2.1.2 or 2.1.3

[dougbu]

Suggest we port the #7770 fix (49c653e) to the next 2.1 patch. Basically [ApiController] causes a regression in some scenarios.

/cc @Eilon @mkArtakMSFT

[mkArtakMSFT]

Given the super simple workaround customers facing this issue can apply, I don't think this will get approved as a patch candidate. Still, I will try to get this approved in Shiproom.

[mkArtakMSFT]

Actually, thinking more about this, this is not even close to the bar for a patch. Closing this.

[dougbu]

@mkArtakMSFT we introduced the #7770 regression in a patch (2.1.1). I'm surprised fix for that doesn't meet the bar for a subsequent patch. We shouldn't break scenarios in a patch -- ever.

In addition, the IFormFileCollection workaround may be simple but isn't particularly obvious.