fix: fix helm prometheus block causing failures (#5458)

helm/templates/coder.yaml

@@ -89,12 +89,20 @@ spec:
               protocol: TCP
             {{- end }}
             {{- range .Values.coder.env }}
-            {{- if and (eq .name "CODER_PROMETHEUS_ENABLE") (eq .value "true") }}
+            {{- if eq .name "CODER_PROMETHEUS_ENABLE" }}
+            {{/*
+            This sadly has to be nested to avoid evaluating the second part
+            of the condition too early and potentially getting type errors if
+            the value is not a string (like a `valueFrom`). We do not support
+            `valueFrom` for this env var specifically.
+            */}}
+            {{- if eq .value "true" }}
             - name: "prometheus-http"
               containerPort: 6060
               protocol: TCP
             {{- end }}
             {{- end }}
+            {{- end }}
           readinessProbe:
             httpGet:
               path: /api/v2/buildinfo