[web] remove PropertySheet._cache
Instead of remembering that a css file has been processed, we re-process it at
every request. This prevents our cache getting out of date with the file
system. Closes #6893185
While we're at it, write the file atomically so that we don't risk serving
partial data.
/var/log/cubicweb/*.log {
weekly
missingok
rotate 10
compress
delaycompress
notifempty
create 640 root adm
sharedscripts
postrotate
if [ -x /usr/sbin/invoke-rc.d ]; then \
invoke-rc.d cubicweb reload > /dev/null 2>&1; \
else \
/etc/init.d/cubicweb reload > /dev/null 2>&1; \
fi; \
endscript
}