Remove the deprecated displayname field from Dashboard extensions

The `displayname` field was deprecated in v0.49.0 LTS.

Remove the remaining code that was added for backwards compatibility.

src/api/extensions.js

@@ -1,5 +1,5 @@
 /*
-Copyright 2019-2024 The Tekton Authors
+Copyright 2019-2025 The Tekton Authors
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
@@ -27,7 +27,6 @@ export function useExtensions(params, queryConfig) {
     data: (data || []).map(({ spec }) => {
       const {
         disableResourceDetailsLinks,
-        displayname, // keep for backwards compatibility for a few releases
         displayName,
         name,
         namespaced
@@ -37,7 +36,7 @@ export function useExtensions(params, queryConfig) {
         apiGroup,
         apiVersion,
         disableResourceDetailsLinks,
-        displayName: displayName || displayname,
+        displayName,
         name,
         namespaced
       };

src/api/extensions.test.js

@@ -1,5 +1,5 @@
 /*
-Copyright 2019-2024 The Tekton Authors
+Copyright 2019-2025 The Tekton Authors
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
@@ -47,37 +47,3 @@ it('useExtensions', () => {
     ]
   });
 });
-
-it('useExtensions displayname backwards compatibility', () => {
-  const name = 'fake_name';
-  const group = 'fake_group';
-  const version = 'fake_version';
-  const apiVersion = `${group}/${version}`;
-  const displayName = 'fake_displayName';
-  const namespaced = true;
-  const query = {
-    data: [{ spec: { apiVersion, displayname: displayName, name, namespaced } }]
-  };
-  const params = { fake: 'params' };
-  vi.spyOn(utils, 'useCollection').mockImplementation(() => query);
-  const extensions = API.useExtensions(params);
-  expect(utils.useCollection).toHaveBeenCalledWith(
-    expect.objectContaining({
-      group: utils.dashboardAPIGroup,
-      kind: 'extensions',
-      params,
-      version: 'v1alpha1'
-    })
-  );
-  expect(extensions).toEqual({
-    data: [
-      {
-        apiGroup: group,
-        apiVersion: version,
-        displayName,
-        name,
-        namespaced
-      }
-    ]
-  });
-});