CloudWatch: the variable editor should accept custom values (#52955) (#53045)

(cherry picked from commit 74f0c3dbd4)

Co-authored-by: Isabella Siu <Isabella.siu@grafana.com>

public/app/plugins/datasource/cloudwatch/components/VariableQueryEditor/VariableQueryEditor.tsx

@@ -122,6 +122,7 @@ export const VariableQueryEditor = ({ query, datasource, onChange }: Props) => {
           onChange={(value: string) => onNamespaceChange(value)}
           label="Namespace"
           inputId={`variable-query-namespace-${query.refId}`}
+          allowCustomValue
         />
       )}
       {parsedQuery.queryType === VariableQueryType.DimensionValues && (
@@ -132,6 +133,7 @@ export const VariableQueryEditor = ({ query, datasource, onChange }: Props) => {
             onChange={(value: string) => onQueryChange({ ...parsedQuery, metricName: value })}
             label="Metric"
             inputId={`variable-query-metric-${query.refId}`}
+            allowCustomValue
           />
           <VariableQueryField
             value={dimensionKey || null}
@@ -139,6 +141,7 @@ export const VariableQueryEditor = ({ query, datasource, onChange }: Props) => {
             onChange={(value: string) => onQueryChange({ ...parsedQuery, dimensionKey: value })}
             label="Dimension key"
             inputId={`variable-query-dimension-key-${query.refId}`}
+            allowCustomValue
           />
           <InlineField label="Dimensions" labelWidth={20} tooltip="Dimensions to filter the returned values on">
             <Dimensions