Switch horizon cache to /var/tmp location

/tmp might be placed in RAM, and many distros (not ubuntu) are doing
in such way. This will prevent horizon from caching files larger
than RAM size.

This patch switched cache directory to /var/tmp.

Change-Id: I9141f5351f5f2368d3387d9c4b4c6cd4fa562b2d
Related-Prod: PROD-25435
2 files changed