Set FLUENT_CONTAINER_TAIL_EXCLUDE_PATH by default to exclude Fluentd logs

[daipom]

Is your feature request related to a problem? Please describe.

• Fluentd logs is full of backslash and kibana doesn't show k8s pods logs fluentd#2545

Describe the solution you'd like

Set FLUENT_CONTAINER_TAIL_EXCLUDE_PATH by default to exclude Fluentd logs.

Describe alternatives you've considered

Users set FLUENT_CONTAINER_TAIL_EXCLUDE_PATH manually.

Additional context

We should use @FLUENT_LOG label to handle Fluentd own logs.
It would not be recommended to collect Fluentd own logs by in_tail.