Remove DiskCache from most places.

DiskCache was introduced as a way to decrease heap size trading out
some performance in exchange.

Now with beefier machines and 64 jvms the memory pressure has gone down
and with per file compiles it is time to reclaim that perforamnce back.
Every second counts.

Change-Id: Ib633b044476252dd71782a222c7d5a1595ba84db
14 files changed