[stable/stackdriver-exporter] Correct servicemonitor name (#16750)

Fixes typo from https://github.com/helm/charts/pull/16372

Signed-off-by: Charlie Egan <charlieegan3@users.noreply.github.com>

stable/stackdriver-exporter/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v1
 description: Stackdriver exporter for Prometheus
 name: stackdriver-exporter
-version: 1.2.0
+version: 1.2.1
 appVersion: 0.6.0
 home: https://www.stackdriver.com/
 sources:

stable/stackdriver-exporter/templates/servicemonitor.yaml

@@ -2,7 +2,7 @@
 apiVersion: monitoring.coreos.com/v1
 kind: ServiceMonitor
 metadata:
-  name: {{ template "prometheus-pushgateway.name" .  }}
+  name: {{ template "stackdriver-exporter.name" .  }}
   {{- if .Values.serviceMonitor.namespace }}
   namespace: {{ .Values.serviceMonitor.namespace }}
   {{- end }}