web: fix event propagation in search-select wrappers (#8224)

web: fix event propogation in search-select wrappers

Two different patches, an older one that extracted long search
blocks that were cut-and-pasted into a standalone component, and a
newer one that fixed displaying placeholder values properly,
conflicted and broke a relationship that allowed for the values to
be propagated through those standalone components correctly.

This restores the event handling and updates the listener set-ups
with more idiomatic hooks into Lit's event system.

web/src/admin/common/ak-core-group-search.ts

@@ -57,7 +57,6 @@ export class CoreGroupSearch extends CustomListenerElement(AKElement) {
         super();
         this.selected = this.selected.bind(this);
         this.handleSearchUpdate = this.handleSearchUpdate.bind(this);
-        this.addCustomListener("ak-change", this.handleSearchUpdate);
     }
 
     get value() {
@@ -94,6 +93,7 @@ export class CoreGroupSearch extends CustomListenerElement(AKElement) {
                 .renderElement=${renderElement}
                 .value=${renderValue}
                 .selected=${this.selected}
+                @ak-change=${this.handleSearchUpdate}
                 ?blankable=${true}
             >
             </ak-search-select>