Remove dependencies on new:ing collections with Guava (refs #2111)

[tomasbjerre]

A small step removing some imports from Guava.

References

#2111

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• The PR request is well described and justified, including the body and the references
• The PR title represents the desired changelog entry
• The repository's code style is followed (see the contributing guide)
• Test coverage that demonstrates that the change works as expected
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[tomasbjerre]

I think the failing Build and test / build (macos-latest, 17) (pull_request) here might be a because of a timing issue, a toggling test case maby?

ResponseTemplateTransformerTest > canHandleALargeTemplateReasonablyFast() FAILED
    java.lang.AssertionError: 
    Expected: a value less than <PT5S>
         but: <PT5.440965S> was greater than <PT5S>
        at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
        at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:6)
        at com.github.tomakehurst.wiremock.extension.responsetemplating.ResponseTemplateTransformerTest.canHandleALargeTemplateReasonablyFast(ResponseTemplateTransformerTest.java:1026)

[Mahoney]

Yes, that's almost certainly just a performance issue... we should probably bump the expectation up to 10 seconds or something to prevent it happening again. The problem it's checking for was making them take minutes, so that should be OK.

[oleg-nenashev]

Created #2259 for the flake, merging: