Add slow_test as it's no longer part of Qiskit 1.0

[woodsp-ibm]

Summary

slow_test used to be part of qiskit.test but the whole test folder was removed for Qiskit 1.0. This adds a copy of that slow_test decorator locally so that things continue working and of course will still work with 0.45 and 0.46 where its deprecated.

Same change as done in qiskit-community/qiskit-algorithms#141

Details and comments

(This seems to be the only apps repo that uses slow_test. I could not find any uses in ML, Opt or Fin.)

[woodsp-ibm]

It seems that algorithms already had a custom dict entry for func which is why similar code there passed. Anyway I added it here.

[coveralls]

Pull Request Test Coverage Report for Build 7745109958

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.01%) to 86.765%

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Files with Coverage Reduction	New Missed Lines	%
qiskit_nature/second_q/drivers/psi4d/psi4driver.py	1	85.12%
<!--	Total:	1		-->

Totals
Change from base Build 7743343685:	-0.01%
Covered Lines:	8785
Relevant Lines:	10125

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💛 - Coveralls