ProjectExplorer: Properly initialize button states in env widget

Fixes: QTCREATORBUG-31483
Change-Id: I773d9daa4eb074fb9c40672c709ece1c0859f649
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/environmentwidget.cpp

@@ -269,6 +269,7 @@ EnvironmentWidget::EnvironmentWidget(QWidget *parent, Type type, QWidget *additi
 
     vbox->addWidget(d->m_detailsContainer);
 
+    updateButtons();
     connect(d->m_model, &QAbstractItemModel::dataChanged,
             this, &EnvironmentWidget::updateButtons);