Fix T82703: Image not scaled when rendering

This is was caused by incorrectly set preview_render_size in VSE
rendering context. Value was set to SEQ_PROXY_RENDER_SIZE_FULL, but
it should be SEQ_PROXY_RENDER_SIZE_SCENE as scene render size is
being used.

This is same fix as 0d7036b40e, but I did not checked openGL
render pipeline.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9562

source/blender/editors/render/render_opengl.c

@@ -493,7 +493,7 @@ static void screen_opengl_render_apply(const bContext *C, OGLRender *oglrender)
                                   scene,
                                   oglrender->sizex,
                                   oglrender->sizey,
-                                  100,
+                                  SEQ_RENDER_SIZE_SCENE,
                                   false,
                                   &context);