Remove invalid configs from memory

Right now if we receive an invalid config update, we keep the existing
config in memory. This makes us remove the existing config so that we
don't have any config for the invalid config key.

Test: atest statsd_test
Bug: 158617758
Change-Id: I9daecb1c96e3a63fea3a45b07d1295f3b4ba452a
4 files changed