Missing filebeats config results in service startup failure

[brendon-stephens]

geerlingguy-filebeat role defaults the filebeats certificate_authorities property to ${filebeat_ssl_certs_dir} if the ${filebeat_ssl_ca_file} property is not provided to ansible.

https://github.com/geerlingguy/ansible-role-filebeat/blob/master/templates/filebeat.yml.j2#L67

This results in a startup failure on both the logs and web servers.

2024-03-25T03:18:08.764Z        INFO    instance/beat.go:292    Setup Beat: filebeat; Version: 7.17.18
2024-03-25T03:18:08.764Z        WARN    [cfgwarn]       tlscommon/config.go:100 DEPRECATED: Treating the CommonName field on X.509 certificates as a host name when no Subject Alternative Names are present is going to be removed. Please update your certificates if needed. Will be removed in version: 8.0.0
2024-03-25T03:18:08.764Z        ERROR   [tls]   tlscommon/tls.go:162    Failed reading CA certificate: read /etc/pki/logstash/: is a directory
2024-03-25T03:18:08.765Z        INFO    instance/beat.go:426    filebeat stopped.
2024-03-25T03:18:08.765Z        ERROR   instance/beat.go:1027   Exiting: error initializing publisher: 1 error: read /etc/pki/logstash/: is a directory reading /etc/pki/logstash/
Exiting: error initializing publisher: 1 error: read /etc/pki/logstash/: is a directory reading /etc/pki/logstash/

Suggested fix is to add the filebeat_ssl_ca_file property to the vars files for both web and elk.

...
filebeat_ssl_ca_file: elk-example.crt