Metrics that are unserializable will be logged at debug level, but the
rest of the batch will be sent.  Unserializable metrics can occur during
normal operation such as if you remove all fields from a metric or the
metric cannot fit within the line size limit.

This has been allowed since 1.1.0

These tests are fundamentally racy, removing to improve reliability of
test cases.

Use "\n" as delimiter as it cannot occur in the series name.

When config dir is mounted from configmap, filepath.Walk() finds the same
.conf file twice as 20-acme.conf is a link to ..data/20-acme.conf for example.

This patch skips all folder names starting with '..' which is pretty
uncommon and mainly used by Kubernetes mounts.