gh-148853: /run/ on my FreeBSD install is not readable causing failing test

[neek78]

In in_systemd_nspawn_sync_suppressed(), we don't catch a PermissionError. This causes test invocation to fail when (for example) /run is not readable. Catch the exception in the same place that a FileNotFoundError is caught.

• Issue: test.support.in_systemd_nspawn_sync_suppressed() fails with permission error #148853

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[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[neek78]

[Updating branch to incorporate the fixes for #149156]