[java] Update rule UseVarargs

[oowekyala]

Describe the PR

Update rule UseVarargs. I think this is the last one of bestpractices, excluding UnusedImports, which I'd like to port much later.

Related issues

• Item of [java] Java-grammar progress document #2701

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by travis)
• Added (in-code) documentation (if needed)

[pmd-test]

	2 Messages
📖	Compared to pmd/7.0.x: This changeset changes 0 violations, introduces 418 new violations, 0 new errors and 0 new configuration errors, removes 0 violations, 0 errors and 0 configuration errors. Full report
📖	Compared to master: This changeset changes 9192 violations, introduces 8331 new violations, 1 new errors and 0 new configuration errors, removes 15657 violations, 10 errors and 2 configuration errors. Full report
✅	Compared to pmd/7.0.x: This changeset changes 0 violations, introduces 330 new violations, 0 new errors and 0 new configuration errors, removes 0 violations, 0 errors and 0 configuration errors. Full report
✅	Compared to master: This changeset changes 2343 violations, introduces 5932 new violations, 1 new errors and 0 new configuration errors, removes 15474 violations, 10 errors and 2 configuration errors. Full report

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