ignore exception in Add-MpPreference
Fix #75482
There are several random exceptions of adding exclusions in Windows Defender https://github.com/pytorch/pytorch/runs/5953410781?check_suite_focus=true
It looks that the Add/Set-MpPreference(added in #75313) might be unstable.
Since it is a defensive step, the exception could be ignored so that the workflow should continue even the command fails.
reference:
https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_commonparameters?view=powershell-7.2
verification:
In the test PR https://github.com/pytorch/pytorch/runs/5966277521?check_suite_focus=true#step:3:54
it tries to delete 2 non-existing processes, but the workflow can continue run.
`-ErrorAction Ignore` works in the runner.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75588
Approved by: https://github.com/suo
