cdkDrag override transform styles

#### Bug, feature request, or proposal:
Bug

#### What is the expected behavior?
When I have transform style on my draggable element, after dragging the transform style will remain.

#### What is the current behavior?
When I have transform style on my draggable element, after start dragging the transform style is overridden.

#### What are the steps to reproduce?
For example add `transform: rotate(45deg);` to `.example-box` here:
https://stackblitz.com/angular/lkdvnnkjmlq?file=src%2Fapp%2Fcdk-drag-drop-overview-example.css
You can notice that after dragging the rotate will disappear.
But, if you will add the `transform: rotate(45deg);` in `style` attribute you will see that the expected behavior is achieved.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
@angular/cdk/drag-drop 8.2.3

Comience con la reproducción vinculada de StackBlitz e inspeccione el manejo de Angular CDK drag-drop para la propiedad transform de .example-box. Confirme que una transformación de la hoja de estilos como rotate(45deg) permanece después de arrastrar, preservando al mismo tiempo el comportamiento demostrado por el ejemplo de estilo inline.

Escrito por el modelo de indexación a partir del texto del issue.