Modify two PyROS solver tests

[shermanjasonaf]

Fixes #2696.

Changes proposed in this PR:

This PR modifies the two PyROS tests discussed in #2696, as follows:

• The models and uncertainty sets are simplified, so that the likelihood of failures arising from subsolver errors in the future is reduced
• IPOPT is used in lieu of BARON/SCIP as the PyROS subsolver (note: in both tests, all PyROS subproblems are now expected to be convex)
• More rigorous checks are performed in both tests

Further, the test pyomo/contrib/pyros/tests/test_grcs.py::testMasterFeasibilityUnitConsistency::test_two_stg_mod_with_axis_aligned_set is renamed to pyomo/contrib/pyros/tests/test_grcs.py::TestAvoidUnitConsistencyChecks::test_avoid_unit_consistency_checks

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.48%. Comparing base (b2463cc) to head (7d73381).
⚠️ Report is 332 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3694      +/-   ##
==========================================
+ Coverage   89.08%   89.48%   +0.40%     
==========================================
  Files         889      894       +5     
  Lines      102746   107520    +4774     
==========================================
+ Hits        91527    96211    +4684     
- Misses      11219    11309      +90     

Flag	Coverage Δ
builders	26.67% <ø> (+0.01%)	⬆️
default	85.66% <ø> (?)
expensive	34.02% <ø> (?)
linux	86.95% <ø> (-1.89%)	⬇️
linux_other	86.95% <ø> (+0.11%)	⬆️
osx	83.25% <ø> (+0.12%)	⬆️
win	85.15% <ø> (?)
win_other	85.15% <ø> (+0.11%)	⬆️

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