Removed 2 unnecessary stubbings in VaultBuildWrapperTest.java

[ARUS2023]

Testing done

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In our analysis of the project, we observed that

1. the test VaultBuildWrapperTest.testWithNonExistingPath contains 1 unnecessary stubbing;
2. the test VaultBuildWrapperTest.getNotFoundResponse contains 1 unnecessary stubbing.

Unnecessary stubbings are stubbed method calls that were never realized during test execution. Mockito recommends to remove unnecessary stubbings (https://www.javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/exceptions/misusing/UnnecessaryStubbingException.html).

We propose below a solution to remove the unnecessary stubbing.