helm: avoid duplicate env var keys in workload env lists (#8488)

* helm: dedupe merged extraEnvironmentVars in workloads

* address comments

Co-Authored-By: Copilot <223556219+Copilot@users.noreply.github.com>

* range

Co-Authored-By: Copilot <223556219+Copilot@users.noreply.github.com>

* helm: reuse merge helper for extraEnvironmentVars

---------

Co-authored-by: Copilot <copilot@github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

k8s/charts/seaweedfs/templates/volume/volume-statefulset.yaml

@@ -118,8 +118,10 @@ spec:
                   fieldPath: status.hostIP
             - name: SEAWEEDFS_FULLNAME
               value: "{{ include "seaweedfs.fullname" $ }}"
-            {{- if $volume.extraEnvironmentVars }}
-            {{- range $key, $value := $volume.extraEnvironmentVars }}
+            {{- $mergedExtraEnvironmentVars := dict }}
+            {{- include "seaweedfs.mergeExtraEnvironmentVars" (dict "global" $.Values.global "component" $volume "target" $mergedExtraEnvironmentVars) }}
+            {{- range $key := keys $mergedExtraEnvironmentVars | sortAlpha }}
+            {{- $value := index $mergedExtraEnvironmentVars $key }}
             - name: {{ $key }}
             {{- if kindIs "string" $value }}
               value: {{ tpl $value $ | quote }}
@@ -128,18 +130,6 @@ spec:
                 {{ toYaml $value | nindent 16 | trim }}
             {{- end -}}
             {{- end }}
-            {{- end }}
-            {{- if $.Values.global.extraEnvironmentVars }}
-            {{- range $key, $value := $.Values.global.extraEnvironmentVars }}
-            - name: {{ $key }}
-            {{- if kindIs "string" $value }}
-              value: {{ tpl $value $ | quote }}
-            {{- else }}
-              valueFrom:
-                {{ toYaml $value | nindent 16 | trim }}
-            {{- end -}}
-            {{- end }}
-            {{- end }}
           command:
             - "/bin/sh"
             - "-ec"