Revert "gddo-server: Use Redis instead of memcache to keep httpcache"

This reverts commit 846822074306e8c6001d10e06fb6f634259b1880.

Reason for revert: Getting error log message about broken client transport, which makes the cache not be able to set to Redis. Investigating this, suspecting this is related to gRPC.

Change-Id: Iac37bf847c433f422463b6d979ca79fb24ce837e
Reviewed-on: https://go-review.googlesource.com/40501
Reviewed-by: Tuo Shan <shantuo@google.com>
339 files changed