…ckage#400)

* Update state tomography benchmarks to use ignis

The state tomography benchmarks have been skipped since terra deprecated
and then removed it's support for doing tomography. The new way to run
tomography is by using ignis. This commit does just that and rewrites
the tomography benchmarks to use ignis instead of terra so that we can
now run them on the current versions of terra.

* Fix lint

* Add a 6 qubit benchmark

* Fix lint again

* Remove setting timer it's already the default

* Increase timeout for state tomography benchmarks

The cat state tomography benchmark for 5 qubits typically takes about 55
seconds for my local desktop. However, sometimes it can take slightly
longer and with a default timeout of 60 seconds it doesn't give much of
a margin.

* Remove 6 qubit benchmark

The 6 qubit cat state tomography benchmark is a bit too slow to be
valuable. On my local desktop it's consistently more than the current
timeout of the state tomography benchmark which is 2min (the bell state
tomography does not have an duration issues, it's minimally slower with
6 qubits). We already have a ton of very slow benchmarks and the
additional value for running tomography with 6 qubits vs 5 is minimal.
So in the interest of time this commit removes the 6 qubit cases.

* Fix lint yet again

…ckage#400)

* Update state tomography benchmarks to use ignis

The state tomography benchmarks have been skipped since terra deprecated
and then removed it's support for doing tomography. The new way to run
tomography is by using ignis. This commit does just that and rewrites
the tomography benchmarks to use ignis instead of terra so that we can
now run them on the current versions of terra.

* Fix lint

* Add a 6 qubit benchmark

* Fix lint again

* Remove setting timer it's already the default

* Increase timeout for state tomography benchmarks

The cat state tomography benchmark for 5 qubits typically takes about 55
seconds for my local desktop. However, sometimes it can take slightly
longer and with a default timeout of 60 seconds it doesn't give much of
a margin.

* Remove 6 qubit benchmark

The 6 qubit cat state tomography benchmark is a bit too slow to be
valuable. On my local desktop it's consistently more than the current
timeout of the state tomography benchmark which is 2min (the bell state
tomography does not have an duration issues, it's minimally slower with
6 qubits). We already have a ton of very slow benchmarks and the
additional value for running tomography with 6 qubits vs 5 is minimal.
So in the interest of time this commit removes the 6 qubit cases.

* Fix lint yet again