Remove test-jar type which is no more used

[apupier]

see apache/camel#21577

[apupier]

the failure is unrelated to this PR, it is already failing on the main branch:

Error:  com.example.demo.DemoApplicationTest.contextLoads
Error:    Run 1: DemoApplicationTest.contextLoads » IllegalState Failed to load ApplicationContext for [WebMergedContextConfiguration@1ddc889b testClass = com.example.demo.DemoApplicationTest, locations = [], classes = [com.example.demo.DemoApplication], contextInitializerClasses = [], activeProfiles = [], propertySourceDescriptors = [], propertySourceProperties = ["org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true"], contextCustomizers = [org.springframework.boot.web.server.context.SpringBootTestRandomPortContextCustomizer@3caa4757, org.springframework.boot.test.context.PropertyMappingContextCustomizer@0, org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@58783f6c, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@33a2499c, org.springframework.boot.test.autoconfigure.OnFailureConditionReportContextCustomizerFactory$OnFailureConditionReportContextCustomizer@1dfd5f51, org.springframework.test.context.support.DynamicPropertiesContextCustomizer@0, org.springframework.boot.test.context.SpringBootTestAnnotation@70461347], resourceBasePath = "src/main/webapp", contextLoader = org.springframework.boot.test.context.SpringBootContextLoader, parent = null]

EDIT: reported https://issues.apache.org/jira/browse/CAMEL-23125