[WIP] Replace old fake v2 backends with new fake v2 backends

[HuangJunye]

Summary

There were older fake BackendV2 classes that were created before for testing. We need to rename, reorganize or remove those classes. See #7838 for details.

This is a work in progress

• FakeBackendV2
• FakeBackendV2LegacyQubitProps
• FakeBackend5QV2
• FakeBackendSimple
• Release note

Details and comments

Fixes #7838

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[mtreinish]

FakeBackend5QV2 is not equivalent to manila in this case. The FakeBackend5QV2 class is designed to provde different combinations of a heterogeneous gate set on a device (where different qubits have different gates defined on them). Primarily to test where different 2q links have different gates available. Most of the tests which are using it are specifically testing that the transpiler is functioning correctly when the backend target is this way. None of the ibm devices are configured this way so there is not an available alternative to this custom class

[HuangJunye]

@mtreinish I see. Let think about how to better deal with the FakeBackend5QV2 class. I think at the minimum we should add a better docstring and rename it to explain the purpose.

Meanwhile I reverted the changes related to this class and try to fix other errors. Do we need the test_run_circuit_oracle_single_experiment_backend test for V2 backends?

https://github.com/Qiskit/qiskit-terra/blob/dde6126e8d8ad550801e9a29adc21c83faf17748/test/python/algorithms/test_backendv2.py#L84-L96

I see these lines were copied from test_backendv1.py (#7563) and those were in turn introduced in #6391. Does V2 backend has max_experiment attribute?

[HuangJunye]

Closing staled PR