Drop application logs from relay-tail

[meain]

What does this PR change?

Previously we were fetching application logs along with audit logs in filebeat. This avoid that by filtering out those using a filebeat preprocessor.

Checklist

I confirm, that I have...

• [x] Read and followed the contributing guide in CONTRIBUTING.md
• [ ] Updated documentation on the Paralus docs site (if applicable)
• [x] Updated CHANGELOG.md
• [ ] Ran helm-docs to update docs for chart (if values.yaml file was changed)