Soften HBS comment; update message to reflect Ember 4.0 removal

The comment "LinkTo always refers to..." overstated our certainty in
classic HBS — a user-defined component could shadow it, though we
can't detect that without resolver info.

The message said "deprecated" but @TagName was fully removed in
Ember 4.0 (deprecation ID: ember.built-in-components.legacy-arguments,
deprecated in 3.27, removed in 4.0.0, Dec 2021).

Author: johanrd

lib/rules/template-no-link-to-tagname.js

@@ -10,7 +10,8 @@ module.exports = {
     },
     schema: [],
     messages: {
-      noLinkToTagname: 'tagName attribute on LinkTo is deprecated',
+      noLinkToTagname:
+        '@tagName on <LinkTo> is not supported (removed in Ember 4.0). <LinkTo> always renders an <a> element.',
     },
     originallyFrom: {
       name: 'ember-template-lint',
@@ -24,7 +25,9 @@ module.exports = {
     const filename = context.filename;
     const isStrictMode = filename.endsWith('.gjs') || filename.endsWith('.gts');
 
-    // In HBS, LinkTo always refers to Ember's router link component.
+    // In HBS, `LinkTo` almost always refers to Ember's router link component; a
+    // user-defined `link-to` could shadow it, but detecting that in classic HBS
+    // would require resolver-level info the rule doesn't have.
     // In GJS/GTS, LinkTo must be explicitly imported from '@ember/routing'
     // (and may be renamed, e.g. `import { LinkTo as Link } from '@ember/routing'`).
     // local alias → true

tests/lib/rules/template-no-link-to-tagname.js

@@ -118,22 +118,22 @@ hbsRuleTester.run('template-no-link-to-tagname', rule, {
     {
       code: '<LinkTo @route="routeName" @tagName="button">Link text</LinkTo>',
       output: null,
-      errors: [{ message: 'tagName attribute on LinkTo is deprecated' }],
+      errors: [{ message: '@tagName on <LinkTo> is not supported (removed in Ember 4.0). <LinkTo> always renders an <a> element.' }],
     },
     {
       code: '<link-to @route="contact" @tagName="div">Contact</link-to>',
       output: null,
-      errors: [{ message: 'tagName attribute on LinkTo is deprecated' }],
+      errors: [{ message: '@tagName on <LinkTo> is not supported (removed in Ember 4.0). <LinkTo> always renders an <a> element.' }],
     },
     {
       code: '{{#link-to "routeName" tagName="button"}}Link text{{/link-to}}',
       output: null,
-      errors: [{ message: 'tagName attribute on LinkTo is deprecated' }],
+      errors: [{ message: '@tagName on <LinkTo> is not supported (removed in Ember 4.0). <LinkTo> always renders an <a> element.' }],
     },
     {
       code: '{{link-to "Link text" "routeName" tagName="button"}}',
       output: null,
-      errors: [{ message: 'tagName attribute on LinkTo is deprecated' }],
+      errors: [{ message: '@tagName on <LinkTo> is not supported (removed in Ember 4.0). <LinkTo> always renders an <a> element.' }],
     },
   ],
 });