fix(eso): chart 0.6.2 - revert fullnameOverride; use templated SA in ClusterSecretStore

Chart 0.6.1's fullnameOverride attempted to give ESO resources stable
names (just 'external-secrets' instead of '<release>-external-secrets')
but ArgoCD couldn't fully drain the prefixed resources from 0.6.0,
leaving sync stuck. Reverting: keep the subchart's default release-
prefixed naming, template the SA reference in ClusterSecretStore via
{{ .Release.Name }}-external-secrets so it resolves correctly per
cluster.

Chart.yaml

@@ -23,8 +23,8 @@ description: |
       Git).
 
 type: application
-version: 0.6.1
-appVersion: "0.6.1"
+version: 0.6.2
+appVersion: "0.6.2"
 
 dependencies:
   - name: cert-manager