[3.14] gh-132124: improve safety nets for creating AF_UNIX socket files (GH-134085) (#134447)

gh-132124: improve safety nets for creating AF_UNIX socket files (GH-134085)

* ensure that we can create AF_UNIX socket files
* emit a warning if system-wide temporary directory is used
(cherry picked from commit 1a07a01014bde23acd2684916ef38dc0cd73c2de)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>