CAMEL-23274: Fix SonarCloud critical bugs in test code

[gnodet]

CAMEL-23274

Fix two critical SonarCloud bugs reported on the main branch:

1. ModelParserTest.java (S5783): Extract ModelParser construction out of the assertThrows lambda so that only parseRoutesDefinition() is the throwing call. Previously both the constructor and the method could throw the same checked exception, making it ambiguous which call caused the exception.

2. EnvironmentHelperTest.java (S5845): Replace assertNotNull(result) with assertDoesNotThrow(...) for three tests where result is a primitive boolean. Comparing a primitive with null via assertNotNull is always true due to autoboxing and does not test anything meaningful.

[github-actions]

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