[Spring] Optimize and omit unnecessary imports on Api in ApiController templates #957

Job	Run time
Build with JDK17 (samples/client/petstore/java-helidon-client/v3/mp/)	1m 5s
Build with JDK17 (samples/client/petstore/spring-http-interface-reactive-noResponseEntity)	38s
Build with JDK17 (samples/openapi3/client/petstore/spring-cloud-3)	1m 6s
Build with JDK17 (samples/client/petstore/spring-http-interface-noResponseEntity)	37s
Build with JDK17 (samples/openapi3/server/petstore/springboot-3)	1m 3s
Build with JDK17 (samples/client/petstore/spring-http-interface-reactive)	42s
Build with JDK17 (samples/client/petstore/spring-http-interface)	41s
Build with JDK17 (samples/client/petstore/java/webclient-jakarta)	57s
Build with JDK17 (samples/server/petstore/java-helidon-server/v3/mp/)	1m 12s
Build with JDK17 (samples/client/petstore/java/microprofile-rest-client-outer-enum)	1m 1s
Build with JDK17 (samples/server/petstore/java-helidon-server/v3/se)	53s
Build with JDK17 (samples/client/petstore/java-helidon-client/v3/se)	56s
Build with JDK17 (samples/server/petstore/java-camel/)	1m 30s
	12m 21s

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