Remove invalid url's and id's from media fixtures

[jorgefilipecosta]

This PR removes invalid URLs and ID's from the fixtures of media blocks making sure we can use these fixtures in the block transforms test case.

A temporary solution to not execute the transforms test cases for these blocks was removed.

Depends on: #14632

How has this been tested?

Verify the end 2 end tests pass.
Verify the fixture test cases pass npm run test-unit test/integration/full-content/full-content.spec.js.

[gziolo]

How about you update the failing test (https://travis-ci.com/WordPress/gutenberg/jobs/187619473#L1011):

Block transforms › should contain the expected transforms

to perform more relaxed check using toMatchObject:

expect(
	transforms
). toMatchObject( EXPECTED_TRANSFORMS );	

[gziolo]

I tried this locally and it seems to work:

it( 'example', () => {
	const actual = {
		core__gallery__columns: {
			availableTransforms: [
				'Slideshow',
				'Image',
			],
			originalBlock: 'Gallery',
		},
	};
	const expected = {
		core__gallery__columns: {
			availableTransforms: expect.arrayContaining( [
				'Image',
			] ),
			originalBlock: 'Gallery',
		},
	};

	expect( actual ).toMatchObject( expected );
} );

[gziolo]

I reviewed it the other day. Now that it is rebased with the latest fix merged to allow us to skip tests when 3rd party plugins are installed, this should be good to go 👍

[gziolo]

Haha 🥇