Fix resource-name override diagnostic wording

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

Author: haiyuazhang

eng/packages/http-client-csharp-mgmt/emitter/src/resource-metadata.ts

@@ -631,7 +631,7 @@ export function applyResourceNameOverrides(
     if (typeof override === "string") {
       if (group.length > 1) {
         diagnosticReporter?.(
-          `@@clientOption(..., "${resourceNameKey}", "${override}", ...) is a plain string but its Read operation produces ${group.length} resources (expandable {parentType}). Use a Record<resourceType, name> map form instead.`
+          `@@clientOption(..., "${resourceNameKey}", "${override}", ...) is a plain string but its Read operation produces ${group.length} resources (expandable {parentType}). Use a Record<enumValue, name> map form instead.`
         );
         continue;
       }

eng/packages/http-client-csharp-mgmt/emitter/test/resource-detection.test.ts

@@ -5001,8 +5001,10 @@ interface PrivateEndpointConnections {
     );
 
     const diagnostics: readonly Diagnostic[] = program.diagnostics;
-    const misuseWarning = diagnostics.find((d) =>
-      d.message.includes("plain string but its Read operation produces")
+    const misuseWarning = diagnostics.find(
+      (d) =>
+        d.message.includes("plain string but its Read operation produces") &&
+        d.message.includes("Record<enumValue, name>")
     );
     ok(
       misuseWarning,