test(centralui): remove stale LoginPage_RendersLdapCredentialHint test

The asserted 'LDAP credentials' tagline was deliberately removed from
Login.razor in f973f49 but the test was not updated alongside. Drop
the test — it asserts on UI text that no longer exists by design.

tests/ScadaLink.CentralUI.Tests/ComponentRenderingTests.cs

@@ -64,14 +64,6 @@ public class ComponentRenderingTests : BunitContext
         Assert.Equal("RequireDesign", attr.Policy);
     }
 
-    [Fact]
-    public void LoginPage_RendersLdapCredentialHint()
-    {
-        var cut = Render<Login>();
-
-        Assert.Contains("LDAP credentials", cut.Markup);
-    }
-
     [Fact]
     public void LoginPage_RendersScadaBridgeTitle()
     {