Remove excess exception logging for minifier, cleanup backend failure exception format (#87537)
Fixes https://github.com/pytorch/torchdynamo/issues/1376
Ensures exceptions are printed only in one place, once.
implements some of the ideas from https://github.com/pytorch/torchdynamo/issues/1754
- Attaches a field to the exception which indicates that it's minified, a usage message is printed if this field is present
cc @jansel @soumith @voznesenskym @yanboliang @penguinwu @anijain2305 @lezcano @fdrocha
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87537
Approved by: https://github.com/anijain2305
