verify that cubeb-related tmp files do not violate disk avoidance
The following bug caught our eye while reviewing undocumented changes made between ESR52 and ESR60 (for legacy/trac#22074 (moved)):
https://bugzilla.mozilla.org/show_bug.cgi?id=1407490 "Ensure cubeb remoting socket has unique name per server process."
From reading the code in media/audioipc/audioipc/src/lib.rs, it looks like temporary files are created in the path returned by
temp_dir() (which is probably /tmp or the %TEMP% directory on Windows). We should see if that is true, what data is in the files, and whether they are left behind when the browser exits.