Wrap calls to deprecated functions in qubit_characterizations_test.py

[mhucka]

Running check/pytest in Python 3.11 on a Debian Linux system produced a few warnings similar to this:

cirq-core/cirq/experiments/qubit_characterizations_test.py::test_parallel_single_qubit_parallel_single_qubit_randomized_benchmarking
   /usr/local/google/home/mhucka/projects/github/cirq-pr-warnings/cirq-core/cirq/experiments/qubit_characterizations_test.py:130: DeprecationWarning: parallel_single_qubit_randomized_benchmarking was used but is deprecated.
   It will be removed in cirq v2.0.
   please use parallel_single_qubit_rb instead

     results = parallel_single_qubit_randomized_benchmarking(

These are not critical, but it is a little bit surprising to see them in Cirq's own unit tests.

This wraps the relevant calls in qubit_characterizations_test.py with the cirq.testing.assert_deprecated(…) context manager to indicate that the deprecation messages are known and expected, and keep them from bubbling up to developers.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.63%. Comparing base (603755a) to head (cf96053).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8031      +/-   ##
==========================================
- Coverage   99.63%   99.63%   -0.01%     
==========================================
  Files        1110     1110              
  Lines       99752    99750       -2     
==========================================
- Hits        99390    99388       -2     
  Misses        362      362              

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[pavoljuhas]

The functions that were initially tested are still supported (until cirq-2) and should be tested. I will post inline workaround shortly.

[pavoljuhas]

This is already imported with cirq so there is no benefit in using a local import. Please revert to module-level imports.

$ python -c "import cirq; print(cirq.experiments.single_qubit_randomized_benchmarking)"
<function single_qubit_randomized_benchmarking at 0x7f30ed960b80>

[pavoljuhas]

We should put back module-level imports. Also, please update the PR title and description. Otherwise LGTM.

[mhucka]

We should put back module-level imports. Also, please update the PR title and description. Otherwise LGTM.

Imports moved in the latest push, and title and body updated to something hopefully more appropriate.