AuraBar: Fix regression in textures after gradient introduction

In ffae60d, instead of adjusting the foreground size and
texture coordinates, we switched to having a frame that clips the
foreground texture, and the code for adjusting the texture coordinates
was removed.

The texture coordinates code actually had 2 jobs, the adjustment to the
foreground size and the rotation of the texture for vertical progress
bars.

Reintroduce the texture coord setting, but only do it on orientation
changes.

Fixes: #4087

WeakAuras/RegionTypes/AuraBar.lua

@@ -263,7 +263,8 @@ local barPrototype = {
     self.directionInverse = (self.orientation == "HORIZONTAL_INVERSE") or (self.orientation == "VERTICAL")
 
     local TLx,  TLy,  BLx,  BLy,  TRx,  TRy,  BRx,  BRy = self.GetTexCoord(0, 1);
-    self.bg:SetTexCoord(TLx , TLy , BLx , BLy , TRx , TRy , BRx , BRy );
+    self.bg:SetTexCoord(TLx, TLy, BLx, BLy, TRx, TRy, BRx, BRy)
+    self.fg:SetTexCoord(TLx, TLy, BLx, BLy, TRx, TRy, BRx, BRy)
 
     -- Set alignment
     self.fgFrame:ClearAllPoints()