Add if conditions to fluentd configuration templates

[pmalek-sumo]

Description

In case user overwrites default values in the following manner (i.e. without specifying a value for keys surround with conditions in this PR)

fluentd:
  buffer:
    extraConf:
...

helm commands might render errors similar to:

Error: template: sumologic/templates/statefulset.yaml:19:28: executing "sumologic/templates/statefulset.yaml" at <include (print $.Template.BasePath "/configmap.yaml") .>: error calling include: template: sumologic/templates/configmap.yaml:15:5: executing "sumologic/templates/configmap.yaml" at <tpl (.Files.Glob "conf/*.conf").AsConfig .>: error calling tpl: error during tpl function execution for "buffer.output.conf: |-\n  compress {{ .Values.fluentd.buffer.compress | quote }}\n  flush_interval {{ .Values.fluentd.buffer.flushInterval | quote }}\n  flush_thread_count {{ .Values.fluentd.buffer.numThreads | quote }}\n  chunk_limit_size {{ .Values.fluentd.buffer.chunkLimitSize | quote }}\n  total_limit_size {{ .Values.fluentd.buffer.totalLimitSize | quote }}\n  queued_chunks_limit_size {{ .Values.fluentd.buffer.queueChunkLimitSize | quote }}\n  overflow_action drop_oldest_chunk\n  retry_max_interval {{ .Values.fluentd.buffer.retryMaxInterval | quote }}\n  retry_forever {{ .Values.fluentd.buffer.retryForever | quote }}\n  {{- .Values.fluentd.buffer.extraConf | nindent 2 }}\ncommon.conf: |-\n  # Prevent fluentd from handling records containing its own logs.\n  <match fluentd.**>\n    @type null\n  </match>\n  # expose the Fluentd metrics to Prometheus\n  <source>\n    @type prometheus\n    metrics_path /metrics\n    port 24231\n  </source>\n  <source>\n    @type prometheus_output_monitor\n  </source>\n  <source>\n    @type http\n    port 9880\n    bind 0.0.0.0\n  </source>\n  {{- if .Values.fluentd.logLevel }}\n  <system>\n    log_level {{ .Values.fluentd.logLevel }}\n  </system>\n  {{- end }}": template: sumologic/templates/statefulset.yaml:11:49: executing "sumologic/templates/statefulset.yaml" at <2>: invalid value; expected string

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Testing performed

• Redeploy fluentd and fluentd-events pods
• Confirm events, logs, and metrics are coming in