Revert private cache enabled by default

[SkewedZeppelin]

Commit caa7ad8 enabled private-cache by default globally.

Should this really be enabled by default? Preventing programs from having persistent cache directories overall has many negative impacts.

• Most email clients cache emails to allow various functionality and downloading them can take many minutes
• Caching makes webpages load faster
• Most music players cache album art from libraries
• Mapping programs (gnome-maps, viking) don't need to constantly redownload tiles
• Mesa shader cache improves graphics load performance
• General waste of bandwith of clients/servers
• General increase in recomputing things
• General potential increase in disk I/O

I think it'd be better if we just manually add private-cache only to suitable programs.

private-cache will need to be added to more programs as identified by

grep 'whitelist ${HOME}/.cache' -L $(grep "private-cache" -L $(grep "redirect" -RiL))

[Fred-Barclay]

I agree. For those of us who want it globally, we can just add private-cache to globals.local.

[netblue30]

Reverted!