Clean up AbstractDependencyMojoTestCase setUp

[Ndacyayisenga-droid]

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Fixes #1486

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[elharo]

I think this one needs the ICKA signed or a commitment to license under apache with the checkbox, or something

[olamy]

I think this one needs the ICKA signed or a commitment to license under apache with the checkbox, or something

Not sure as most of the code is for src/test/.
But why not ICLA if @Ndacyayisenga-droid is happy to do it. See here https://www.apache.org/licenses/contributor-agreements.html#submitting