fix DSpace#5544: enlarge dropdown for external source import

(cherry picked from commit 1f582d1)

Author: guillermo-escire

src/app/submission/import-external/import-external-searchbar/submission-import-external-searchbar.component.scss

@@ -13,8 +13,9 @@
 
 .scrollable-menu {
   height: auto;
-  max-height: calc(var(--ds-dropdown-menu-max-height) / 2);
+  max-height: calc(var(--ds-dropdown-menu-max-height) * 2);
   overflow-x: hidden;
+  overflow-y: auto;
 }
 
 .scrollable-dropdown-loading {

src/app/submission/import-external/import-external-searchbar/submission-import-external-searchbar.component.spec.ts

@@ -140,17 +140,25 @@ describe('SubmissionImportExternalSearchbarComponent test suite', () => {
       expect(comp.selectedElement).toEqual(selectedElement);
     });
 
+    it('Should use elementsPerPage of 20 on init', () => {
+      comp.initExternalSourceData = { entity: 'Publication', sourceId: '', query: '' };
+      scheduler.schedule(() => fixture.detectChanges());
+      scheduler.flush();
+
+      expect(compAsAny.findListOptions.elementsPerPage).toEqual(20);
+    });
+
     it('Should load additional external sources', () => {
       comp.initExternalSourceData = { entity: 'Publication', query: 'dummy', sourceId: 'ciencia' };
       comp.sourceListLoading = false;
       compAsAny.pageInfo = new PageInfo({
-        elementsPerPage: 3,
+        elementsPerPage: 20,
         totalElements: 6,
         totalPages: 2,
         currentPage: 0,
       });
       compAsAny.findListOptions = Object.assign({}, new FindListOptions(), {
-        elementsPerPage: 3,
+        elementsPerPage: 20,
         currentPage: 0,
         searchParams: [
           new RequestParam('entityType', 'Publication'),

src/app/submission/import-external/import-external-searchbar/submission-import-external-searchbar.component.ts

@@ -143,7 +143,7 @@ export class SubmissionImportExternalSearchbarComponent implements OnInit, OnDes
     this.searchString = '';
     this.sourceList = [];
     this.findListOptions = Object.assign({}, new FindListOptions(), {
-      elementsPerPage: 5,
+      elementsPerPage: 20,
       currentPage: 1,
       searchParams: [
         new RequestParam('entityType', this.initExternalSourceData.entity),
@@ -188,7 +188,7 @@ export class SubmissionImportExternalSearchbarComponent implements OnInit, OnDes
     if (!this.sourceListLoading && ((this.pageInfo.currentPage + 1) <= this.pageInfo.totalPages)) {
       this.sourceListLoading = true;
       this.findListOptions = Object.assign({}, new FindListOptions(), {
-        elementsPerPage: 5,
+        elementsPerPage: 20,
         currentPage: this.findListOptions.currentPage + 1,
         searchParams: [
           new RequestParam('entityType', this.initExternalSourceData.entity),