a) Description of problem:

While sending specific namespace logs to an external aggregator as well as send logs to
internal OCP Elasticsearch(default) using the built-in application, the internal OCP ES
can not see the specific namespace logs.

b) Version-Release number of selected component (if applicable):

OpenShift 4.7 and OpenShift Logging 5.0

c) How reproducible:

Always when sending specific namespace logs

d) Steps to Reproduce:

1. Deploy OpenShift Logging(Elasticsearch operator and OpenShift Logging Operator)
2. Create a cluster logging instance
3. Configure ClusterLogForwarder with the following yaml
~~~
apiVersion: logging.openshift.io/v1
kind: ClusterLogForwarder
metadata:
  name: instance
spec:
  inputs:
    - application:
        namespaces:
         - test
      name: test-app-logs
  outputs:
   - name: rsyslog
     type: syslog
     syslog:
       facility: local0
       severity: informational
     url: 'udp://<rsyslog server>'
  pipelines:
    - name: application-default
      inputRefs:
        - application
      outputRefs:
        - default
    - name: forward-to-syslog
      inputRefs:
        - test-app-logs
      outputRefs:
        - rsyslog
~~~
4. Check the forwarded logs from the "application-default" pipeline

e) Actual results:
The forwarded logs from the built-in "application" doesn't include the specific namespace logs

f) Expected results:
All the application logs should be forwarded using the built-in application 
type while sending specific namespace logs

g) Additional info:

In OpenShift Logging 5.1 or later, this behavior is changed to send all the application
logs while sending specific namespace logs by the following commit:

https://github.com/openshift/cluster-logging-operator/pull/999

But, as for OpenShift Logging 5.1 and later, the namespace filtering feature is
changed based on label router plugin.
So we can not cherry-pick cluster-logging-operator#999 to 5.0 and 4.6 simply.

The following PR is the change for OpenShift Logging 5.0.
It depends on https://github.com/openshift/cluster-logging-operator/pull/976.