[TIMOB-27117] Android: TabGroup bar's background color is wrongly transparent on Android 4.4 as of 8.0.0

*Summary:* As of Titanium 8.0.0, the TabGroup tab bar's background color is transparent on Android 4.4. On Android 5.0 and higher, it shows the correct background color (defaults to dark gray). This issue happens with both the top and bottom tab bar styles. *Steps to reproduce:*

Set up a Classic Titanium app project with the below code.

Build with Titanium 8.0.0 and run it on Android 4.4

Observe the displayed tab bar.

function createTab(title) {
	var window = Ti.UI.createWindow({ title: title });
	window.add(Ti.UI.createLabel({ text: title + " View" }));
	var tab = Ti.UI.createTab({
		title: title,
		window: window,
	});
	return tab;
}

var tabGroup = Ti.UI.createTabGroup({
	tabs: [createTab("Tab 1"), createTab("Tab 2"), createTab("Tab 3")],
//	style: Ti.UI.Android.TABS_STYLE_BOTTOM_NAVIGATION,
});
tabGroup.open();

*Result:* The TabGroup tab bar's background color is transparent when it shouldn't be. !TabGroup-bad.png|thumbnail! *Expected Result:* The tab bar should use the same background color as the ActionBar, which by default is dark gray (depending on the assigned theme). !TabGroup-good.png|thumbnail! *Work-around:* Set TabGroup property "tabsBackgroundColor" to the color you want. The original dark gray color is "#FF212121".