Axivion: Fix hiding columns

Originally the key had been used as header values, but
nowadays we may use the display name if it is present.
This broke the logic that hid columns on first fetch.

Change-Id: I567f0ca79b0691750dc4a2e8a45ff0479a94e0fd
Reviewed-by: hjk <hjk@qt.io>

src/plugins/axivion/axivionperspective.cpp

@@ -520,7 +520,7 @@ void IssuesWidget::updateTable()
     for (const Dto::ColumnInfoDto &column : m_currentTableInfo->columns) {
         columnHeaders << column.header.value_or(column.key);
         if (!column.showByDefault)
-            hiddenColumns << column.key;
+            hiddenColumns << columnHeaders.last();
         IssueHeaderView::ColumnInfo info;
         info.key = column.key;
         info.sortable = column.canSort;