chore: delete junit3 reference

[sparsick]

• updated test to junit5
• delete dead code

[sparsick]

some test related code like maven-it-plugin-error use JUnit 3 classes. Any hints what is the best way to replace them?

For example,

maven/its/core-it-support/core-it-plugins/maven-it-plugin-error/src/main/java/org/apache/maven/plugin/coreit/RequirementComponentLookupExceptionMojo.java

Line 35 in fb61929

@Component(role = TestCase.class, hint = "triggers-error")

cc @slawekjaranowski