fix(helm): Add Elastic APM 8 style API key environment variable support

Author: nellh

helm/openneuro/templates/secret.yaml

@@ -40,3 +40,4 @@ stringData:
   ELASTICSEARCH_CLOUD_ID: {{ .Values.secrets.elasticsearch.ELASTICSEARCH_CLOUD_ID | quote }}
   ELASTICSEARCH_CLOUD_AUTH: {{ .Values.secrets.elasticsearch.ELASTICSEARCH_CLOUD_AUTH | quote }}
   ELASTIC_APM_SECRET_TOKEN: {{ .Values.secrets.elasticsearch.ELASTIC_APM_SECRET_TOKEN | quote }}
+  ELASTIC_APM_API_KEY: {{ .Values.secrets.elasticsearch.ELASTIC_APM_API_KEY | quote }}