[BE] Set PYTORCH_TEST_WITH_INDUCTOR only once (#94411)
Setting the same env-var twice should have no effect, unless one is trying mini rowhammer here
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94411
Approved by: https://github.com/jeanschmidt, https://github.com/huydhn, https://github.com/Skylion007
