chore: 🔨 refactor Makefile to standardize clean target naming conventions

Author: tmeckel

Makefile

@@ -1,16 +1,16 @@
 .PHONY: default
 default: build
 
-.PHONY: java-clean
-java-clean:
+.PHONY: clean/java
+clean/java:
 	docker run --pull always -t --rm -v maven-repo:/root/.m2 -v "${PWD}":/work -w /work maven:3-eclipse-temurin-11 mvn clean
 
-.PHONY: docker-clean
-docker-clean:
+.PHONY: clean/docker
+clean/docker:
 	docker rmi -f openapi-generator-di:dev
 
 .PHONY: clean
-clean: java-clean docker-clean
+clean: clean/java clean/docker
 	rm -rf tests/.generated*
 
 .PHONY: build