recovery: Handle devices without /cache partition.

Since we may not have /cache partition on A/B devices, let recovery
handle /cache related operations gracefully if /cache doesn't exist.

(1) Disable the wipe for /cache partition.

(2) Skip wiping /cache while wiping /data (i.e. factory reset).

(3) Disable logging-related features, until we figure out better
ways / places to store recovery logs (mainly for factory resets on A/B
devices).

Bug: 27176738
Change-Id: I7b14e53ce18960fe801ddfc15380dac6ceef1198