tst_textfield: fix warnings

Fix all warnings encountered in test run:

- in test_alignment()
QWARN Could not set initial property horizontalAlignment

- in test_font_explicit_attributes(family)
QWARN qt.qpa.fonts: Populating font family aliases took 130 ms. Replace
uses of missing font family "Courier" with one that exists to avoid this
cost.

Fixes: QTBUG-119646
Pick-to: 6.7 6.6 6.5
Change-Id: I34edb8a8c85ad134f3a8844463722f71bd30bc1b
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

tests/auto/quickcontrols/controls/data/tst_textfield.qml

@@ -154,10 +154,12 @@ TestCase {
     }
 
     function test_alignment(data) {
-        var control = createTemporaryObject(textField, testCase, {text: data.text, placeholderText: data.placeholderText, horizontalAlignment: data.textAlignment})
+        var control = createTemporaryObject(textField, testCase, {text: data.text, placeholderText: data.placeholderText})
 
-        if (data.textAlignment !== undefined)
+        if (data.textAlignment !== undefined) {
+            control.horizontalAlignment = data.textAlignment
             compare(control.horizontalAlignment, data.textAlignment)
+        }
         // The placeholder text of the Material style doesn't currently respect the alignment of the control.
         if (StyleInfo.styleName !== "Material") {
             for (var i = 0; i < control.children.length; ++i) {
@@ -180,7 +182,7 @@ TestCase {
         return [
             {tag: "bold", value: true},
             {tag: "capitalization", value: Font.Capitalize},
-            {tag: "family", value: "Courier"},
+            {tag: "family", value: "Tahoma"},
             {tag: "italic", value: true},
             {tag: "strikeout", value: true},
             {tag: "underline", value: true},