[fenix] For https://github.com/mozilla-mobile/fenix/issues/23245 - Replace @color/inset_private_theme with @color/fx_mobile_private_layer_color_1

app/src/main/res/values/colors.xml

@@ -147,7 +147,6 @@
     <color name="secondary_text_private_theme">#A7A2B7</color>
     <color name="caption_text_private_theme">@color/photonLightGrey70</color>
     <color name="foundation_private_theme">#261E4B</color>
-    <color name="inset_private_theme">@color/photonInk50</color>
     <color name="accent_private_theme">@color/photonViolet50</color>
     <color name="accent_bright_private_theme">@color/photonViolet70</color>
     <color name="accent_high_contrast_private_theme">#AA71FF</color>

app/src/main/res/values/styles.xml

@@ -236,7 +236,7 @@
         <item name="accentHighContrast">@color/accent_high_contrast_private_theme</item>
         <item name="foundation">@color/foundation_private_theme</item>
         <item name="above">@color/fx_mobile_private_layer_color_1</item>
-        <item name="inset">@color/inset_private_theme</item>
+        <item name="inset">@color/fx_mobile_private_layer_color_1</item>
         <item name="tabRing">@color/tab_ring_private_theme</item>
         <item name="neutral">@color/neutral_private_theme</item>
         <item name="neutralFaded">@color/neutral_faded_private_theme</item>