Simplify OverviewActionsView layout to avoid unexpected misalignemnt

- Removed the weight=3 space on left/right and replace with gracvity=central_horizontal
- Removed unused oav_three_button_space
- Removed irrelevant layout_gravity (gravity within parent), as the LinearLayout is already taking full parent width, and its vertical alignemnt si controlled by `updateVerticalMargin` in code

Bug: 329255757
Test: OverviewImageTest
Flag: None
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:2cf1a0c08d41ee7a29ea920c93850d3914ed7cd8)
Merged-In: Ice087dde7d3c36b4536d36ce82c382c31c124855
Change-Id: Ice087dde7d3c36b4536d36ce82c382c31c124855

quickstep/res/layout/overview_actions_container.xml

@@ -23,14 +23,9 @@
         android:id="@+id/action_buttons"
         android:layout_width="match_parent"
         android:layout_height="@dimen/overview_actions_height"
-        android:layout_gravity="bottom|center_horizontal"
+        android:gravity="center_horizontal"
         android:orientation="horizontal">
 
-        <Space
-            android:layout_width="0dp"
-            android:layout_height="1dp"
-            android:layout_weight="1" />
-
         <Button
             android:id="@+id/action_screenshot"
             style="@style/OverviewActionButton"
@@ -63,18 +58,6 @@
             android:text="@string/action_save_app_pair"
             android:theme="@style/ThemeControlHighlightWorkspaceColor"
             android:visibility="gone" />
-
-        <Space
-            android:layout_width="0dp"
-            android:layout_height="1dp"
-            android:layout_weight="1" />
-
-        <Space
-            android:id="@+id/oav_three_button_space"
-            android:layout_width="0dp"
-            android:layout_height="1dp"
-            android:layout_weight="1"
-            android:visibility="gone" />
     </LinearLayout>
 
 </com.android.quickstep.views.OverviewActionsView>