Tests

Adds `mul` and `rmul` methods to `SparseHamiltonian` #39040

Job	Run time
tests / setup-ci-load	1s
tests / autograd-tests (3.9) / autograd-tests (3.9)	1m 33s
tests / jax-tests (1, 3.9) / jax-tests (1, 3.9)	1m 31s
tests / jax-tests (2, 3.9) / jax-tests (2, 3.9)	1m 32s
tests / jax-tests (3, 3.9) / jax-tests (3, 3.9)	2m 21s
tests / all-interfaces-tests (3.9) / all-interfaces-tests (3.9)	1m 32s
tests / jax-tests (4, 3.9) / jax-tests (4, 3.9)	1m 32s
tests / core-tests (1, 3.9) / core-tests (1, 3.9)	1m 31s
tests / tf-tests (1, 3.9) / tf-tests (1, 3.9)	1m 19s
tests / jax-tests (5, 3.9) / jax-tests (5, 3.9)	1m 31s
tests / tf-tests (2, 3.9) / tf-tests (2, 3.9)	1m 29s
tests / tf-tests (3, 3.9) / tf-tests (3, 3.9)	1m 26s
tests / torch-tests (3.9) / torch-tests (3.9)	1m 31s
tests / core-tests (2, 3.9) / core-tests (2, 3.9)	1m 30s
tests / data-tests (3.9) / data-tests (3.9)	2m 22s
tests / qcut-tests (3.9) / qcut-tests (3.9)	1m 31s
tests / device-tests (default.qubit.legacy, None, 3.9) / device-tests (default.qubit.legacy, None, 3.9)	55s
tests / external-libraries-tests (3.9) / external-libraries-tests (3.9)	1m 29s
tests / gradients-tests (finite-diff, 3.9) / gradients-tests (finite-diff, 3.9)	1m 28s
tests / gradients-tests (param-shift, 3.9) / gradients-tests (param-shift, 3.9)	1m 29s
tests / qchem-tests (3.9) / qchem-tests (3.9)	1m 28s
tests / device-tests (default.qubit.legacy, 10000, 3.9) / device-tests (default.qubit.legacy, 10000, 3.9)	26s
tests / upload-to-codecov	1s
	31m 28s

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