Address reviewer feedback

- remove redundant issuable_tabs logic
- set issuesListLoading to false initially

app/assets/javascripts/issuable_list/components/issuable_tabs.vue

@@ -27,7 +27,7 @@ export default {
       return tabName === this.currentTab;
     },
     isTabCountNumeric(tab) {
-      return this.tabCounts ? Number.isInteger(this.tabCounts[tab.name]) : false;
+      return Number.isInteger(this.tabCounts[tab.name]);
     },
   },
 };

ee/app/assets/javascripts/integrations/jira/issues_list/components/jira_issues_list_root.vue

@@ -51,7 +51,7 @@ export default {
     return {
       jiraLogo,
       issues: [],
-      issuesListLoading: true,
+      issuesListLoading: false,
       issuesListLoadFailed: false,
       totalIssues: 0,
       currentState: this.initialState,

ee/spec/frontend/integrations/jira/issues_list/components/jira_issues_list_root_spec.js

@@ -53,11 +53,13 @@ describe('JiraIssuesListRoot', () => {
 
   describe('on mount', () => {
     describe('while loading', () => {
-      it('sets issuesListLoading to `true`', () => {
+      it('sets issuesListLoading to `true`', async () => {
         jest.spyOn(axios, 'get').mockResolvedValue(new Promise(() => {}));
 
         createComponent();
 
+        await wrapper.vm.$nextTick();
+
         const issuableList = findIssuableList();
         expect(issuableList.props('issuablesLoading')).toBe(true);
       });