Aconfigd: send an error message back thru socket in case of error am: cdf0f5c61f am: 63c8209e9a

Original change: https://android-review.googlesource.com/c/platform/system/server_configurable_flags/+/3371875

Change-Id: I177ba7ab4706da61e33f35024efcc4d8c2cac5a0
Signed-off-by: Automerger Merge Worker <[email protected]>