Use list for sub issues (#2514)

Signed-off-by: Andrey Sobolev <haiodo@gmail.com>

plugins/tracker-resources/src/components/issues/edit/SubIssueSelector.svelte

@@ -92,7 +92,7 @@
 
   $: areSubIssuesLoading = !subIssues
   $: parentIssue = issue.$lookup?.attachedTo ? (issue.$lookup?.attachedTo as Issue) : null
-  $: if (parentIssue) {
+  $: if (parentIssue && parentIssue.subIssues > 0) {
     subIssuesQeury.query(
       tracker.class.Issue,
       { space: issue.space, attachedTo: parentIssue._id },
@@ -113,6 +113,7 @@
 {#if parentIssue}
   <div class="flex root">
     <div class="item clear-mins">
+      <!-- svelte-ignore a11y-click-events-have-key-events -->
       <div
         class="flex-center parent-issue cursor-pointer"
         use:tooltip={{ label: tracker.string.OpenParent, direction: 'bottom' }}
@@ -136,6 +137,7 @@
           <Spinner size="small" />
         </div>
       {:else}
+        <!-- svelte-ignore a11y-click-events-have-key-events -->
         <div
           bind:this={subIssuesElement}
           class="flex-center sub-issues cursor-pointer"