Fix: Operator, app template and benchmarking script errors after media type

Always set the media type before the file format.

Ref #142955

Pull Request: https://projects.blender.org/blender/blender/pulls/143433

tests/python/bl_imbuf_load.py

@@ -73,6 +73,7 @@ class ImBufTest(AbstractImBufTest):
     def _save_exr(self, img, out_exr_path):
         scene = bpy.data.scenes[0]
         image_settings = scene.render.image_settings
+        image_settings.media_type = 'IMAGE'
         image_settings.file_format = "OPEN_EXR"
         image_settings.color_mode = "RGBA"
         image_settings.color_depth = "32"

tests/python/bl_mesh_modifiers.py

@@ -33,6 +33,7 @@ def render_gl(context, filepath, shade):
     scene = context.scene
     render = scene.render
     render.filepath = filepath
+    render.image_settings.media_type = 'IMAGE'
     render.image_settings.file_format = 'PNG'
     render.image_settings.color_mode = 'RGB'
     render.use_file_extension = True