layer.remove() does not remove marker from the map

[oliverroick]

Describe the bug
Removing a layer using layer.remove() does not remove the layer's marker from the map.

To Reproduce
Test case:

it('L.Polygon.remove() removes marker from the map', () => {
  deflateLayer.addTo(map);
  deflateLayer.addLayer(polygon);
  map.setZoom(10, { animate: false });
  polygon.remove();
  expect(map.hasLayer(polygon)).toBeFalsy();
  expect(map.hasLayer(polygon.marker)).toBeFalsy();
});

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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Example
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Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.