webgl: Remove manual Drop implementation for WebGLQuery (#43544)

Moves the cleanup logic to a separate helper struct to comply with the
prohibition of manual `Drop` implementations for DOM types.

Testing: WebGL tests just cover its parts
Fixes: Partially #26488

Signed-off-by: Domenico Rizzo <domenico.rizzo@gmail.com>

components/script_bindings/codegen/Bindings.conf

@@ -824,10 +824,6 @@ DOMInterfaces = {
     'additionalTraits': ['crate::interfaces::WebGL2RenderingContextHelpers'],
 },
 
-'WebGLQuery': {
-    'allowDropImpl': True,
-},
-
 'WebGLRenderbuffer': {
     'allowDropImpl': True,
 },