Clean up unused templates

[sumo-drosiek]

The following command returns unused templates:

> for i in $(cat templates/_helpers/*.tpl | grep define | grep -oP '".*?"'); do if grep -P "(template|include) ${i}" . -R > /dev/null; then; else  echo $i; fi; done
"sumologic.name"
"sumologic.sumo_client"
"logs.collector.otelcloudwatch.enabled"
"sumologic.labels.metrics.remoteWriteProxy"
"sumologic.labels.app.metrics.collector.pod"
"terraform.sources.endpoint_name"
"sumologic.labels.app.tracessampler.service-metrics"
"sumologic.labels.app.otelcolinstrumentation.statefulset"
"sumologic.labels.app.tracesgateway.deployment"