Fix mppi bidirectional settings

[mini-1235]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#4601
Primary OS tested on	Ubuntu
Robotic platform tested on	gazebo sim
Does this PR contain AI generated software?	NO

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Description of contribution in a few bullet points

• Fix the acceleration and deceleration when going backward as mentioned in the issue, mostly copied from [velocity_smoother] Fix accel and deccel inverted for negative speeds #3529
• Regarding the performance issue mentioned in the issue, I ran benchmark and observed no significant difference from the original(tested with different parameters)

Description of documentation updates required from your changes

None

Description of how this change was tested

Tested on sim, wrote some new unit tests

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Future work that may be required in bullet points

Maybe more unit tests? Looking for some suggestions before proceeding

For Maintainers:

• Check that any new parameters added are updated in docs.nav2.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
...ler/include/nav2_mppi_controller/motion_models.hpp	100.00% <100.00%> (ø)
nav2_mppi_controller/src/optimizer.cpp	99.19% <100.00%> (+<0.01%)	⬆️

... and 3 files with indirect coverage changes