Remove psutil as a dependency

[FabianBrings]

Summary

Removes any uses of psutil and the corresponding dependency

Details and comments

As described in issue #11254, psutil is used to detect the number of cores and memory to optimize resource allocation. The actual usefulness of those information is however questionable, while adding additional bloat. Therefore any references to the module were modified, the unit tests fixed and the dependency removed.

Fixes #11254

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• Overall coverage decreased (-0.03%) to 89.482%

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Totals
Change from base Build 7614776689:	-0.03%
Covered Lines:	59473
Relevant Lines:	66464

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💛 - Coveralls

[FabianBrings]

The test that fails is "test_handle_measurement" while performing SabreSwaps. I can reproduce the error, by setting QISKIT_NUM_PROCS=1. SabreSwap uses CPU_COUNT to determine the number of runs while evaluating the heuristic to optimize the circuit. The new method of finding the cpu count probably yields a different, platform-dependent result and therefore the heuristic returns another result. This raises the question, how this test case should be handled. If the reference circuit is not reached depending on system parameters, it is not a sensible test case, but hard overwriting the cpu count with two, just to make this case work seems equally nonsensical. How would you like to proceed?

[mtreinish]

It's a bug in the test, we should be setting a fixed number of trials to ensure the test is deterministic. So I'd suggest ust hardcoding the trial count in the test.

[mtreinish]

Overall this LGTM, thanks for tackling this. I just had a few inline comments.

[mtreinish]

Thanks for opening the PR. I just pushed up some small commits to update the tests and apply my inline suggestions to get this unblocked

[FabianBrings]

Thanks a lot for approving my PR and for helping out with the small fixes!