Fix context usage (#33554)

Some old code use direct type-casting to get context, it causes
problems.

This PR fixes all legacy problems and use correct `ctx.Value` to get
low-level contexts.

Fix #33518

services/contexttest/context_tests.go

@@ -67,7 +67,7 @@ func MockContext(t *testing.T, reqPath string, opts ...MockContextOption) (*cont
 
 	chiCtx := chi.NewRouteContext()
 	ctx := context.NewWebContext(base, opt.Render, nil)
-	ctx.SetContextValue(context.WebContextKey, ctx)
+	ctx.SetContextValue(context.WebContextKey, ctx) // FIXME: this should be removed because NewWebContext should already set it
 	ctx.SetContextValue(chi.RouteCtxKey, chiCtx)
 	if opt.SessionStore != nil {
 		ctx.SetContextValue(session.MockStoreContextKey, opt.SessionStore)