tests/functional: Introduce a specific test for rainier-bmc machine This simply moves the rainier-bmc test to a new test file. No changes in the test. The test_arm_aspeed.py is deleted. Reviewed-by: Thomas Huth <thuth@redhat.com> Link: https://lore.kernel.org/r/20241206131132.520911-7-clg@redhat.com Signed-off-by: Cédric Le Goater <clg@redhat.com>