Reduce the number of iterations in test_autograd_context (#35037)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35037
Closes #34960
Cannot reproduce the test failure in dev server, local machine, and
the CI env that captured the failure. However, the failed test takes
very long (~10sec) in MacOS, so reducing the number of iterations to
make it lighter.
Re-enable the test and will monitor if the error occurs again.
Test Plan: Imported from OSS
Differential Revision: D20536272
Pulled By: mrshenli
fbshipit-source-id: 577822574e5f6271f1cbb14b56c68c644291713e
