fix(ui5-li-tree): fixed incorrect display of the text (#3036)

While the TreeListItem is in its _minimal state (with no visible
text), the text was still taking space, causing incorrect alignment
of the icons. Now the text is not rendered when we are in _minimal state
which results in proper alignment of the icons.

packages/main/src/themes/TreeListItem.css

@@ -33,6 +33,10 @@
     bottom: 0.125rem;
 }
 
+:host([_minimal]) .ui5-li-tree-text-wrapper {
+	display: none;
+}
+
 .ui5-li-root-tree {
     padding-left: 0;
 }