fix(select): ensure md-select selection logic uses fresh DOM references

Previously selectItem would work with cached references to select-option elements which could become stale causing the deactivation logic to fail. This cl just ensures that selectItem always re-fetches the nodes to avoid the issue.

PiperOrigin-RevId: 595524158

Author: material-web-copybara

select/internal/select.ts

@@ -725,7 +725,8 @@ export abstract class Select extends selectBaseClass {
    * @return Whether the last selected option has changed.
    */
   private selectItem(item: SelectOption) {
-    this.lastSelectedOptionRecords.forEach(([option]) => {
+    const selectedOptions = this.getSelectedOptions() ?? [];
+    selectedOptions.forEach(([option]) => {
       if (item !== option) {
         option.selected = false;
       }