Fix flaky mppi test

[mini-1235]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#4932
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

• Fixed the flaky test as mentioned in the issue, added a new one for non-regenerate noise

Description of documentation updates required from your changes

Description of how this change was tested

Unit test, run around 10000 rounds

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Future work that may be required in bullet points

Currently in noise generator we have 3 tests, the first test NoiseGeneratorLifecycle is actually covered by my new one, should we delete this test or keep it?

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 ✅

see 4 files with indirect coverage changes