[ENG-5046] Preprints selectors part 2 (#2102)

## Purpose

The previous PR got merged before it was completely through QA, so this contains the other test selectors that were requested.

## Summary of Changes

1. Add data-test-selectors for withdrawal justification

Author: brianjgeiger

app/preprints/-components/preprint-tombstone/template.hbs

@@ -1,8 +1,8 @@
 <div local-class='withdrawn-container'>
     {{#if @preprint.withdrawalJustification}}
-        <div>
+        <div data-test-withdrawal-justification>
             <h4>{{t 'preprints.detail.reason_for_withdrawal'}}</h4>
-            <p>
+            <p data-test-justification>
                 {{@preprint.withdrawalJustification}}
             </p>
         </div>