android: Make a constant static

... and use uppercase letters for its name.

Change-Id: Ib10b792d55928223d7484b7fb339ca252532bc28
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/194197
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

android/source/src/java/org/libreoffice/overlay/DocumentOverlay.java

@@ -32,7 +32,7 @@ public class DocumentOverlay {
     private final DocumentOverlayView mDocumentOverlayView;
     private final DocumentOverlayLayer mDocumentOverlayLayer;
 
-    private final long hidePageNumberRectDelayInMilliseconds = 500;
+    private static final long HIDE_PAGE_NUMBER_RECT_DELAY_IN_MILLISECONDS = 500;
 
     /**
      * DocumentOverlayLayer responsibility is to get the changes to the viewport
@@ -118,7 +118,7 @@ public class DocumentOverlay {
             public void run() {
                 mDocumentOverlayView.hidePageNumberRect();
             }
-        }, hidePageNumberRectDelayInMilliseconds);
+        }, HIDE_PAGE_NUMBER_RECT_DELAY_IN_MILLISECONDS);
     }
 
     /**