test: stabilize crud lumo visual tests by disabling backdrop animation (#11587)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: web-padawan

packages/crud/test/not-animated-styles.js

@@ -6,7 +6,8 @@ registerStyles(
     :host([opening]),
     :host([closing]),
     :host([opening]) [part='overlay'],
-    :host([closing]) [part='overlay'] {
+    :host([closing]) [part='overlay'],
+    [part='backdrop'] {
       animation: none !important;
     }
   `,