Improve Spring configuration

Is your feature request related to a problem? Please describe.
The APIML uses a couple of deprecated configurations of Spring. The aim of this issue is to reduce them and replace them properly.

• spring.config.useLegacyProcessing
  • remove legacy mode
  • replace the deprecated configuration values with the new replacement
  • https://spring.io/blog/2020/08/14/config-file-processing-in-spring-boot-2-4
  • spring.profiles > spring.config.activate.on-profile
  • use spring.profiles.group.* instead of spring.profiles.include
  • ensure that no value is marked as deprecated after the change (and fixing them)
• spring.mvc.favicon.enabled
  • remove this config value
  • ensure that each service serves an APIML favicon
• spring.cloud.compatibilityVerifier
  • verify if this configuration value is still required
• spring.main.allow-circular-references
  • see creating Jersey client in the HttpConfig bean
    • it could be solved by the lazy creation of the bean
  • fields meAsProxy to handle cache aspects
    • could be done by: different type of proxy / post bean factory handler / new aspect
    • find the best way and replace it

Start by reviewing the Spring configuration values listed in the issue and the HttpConfig bean, including the Jersey client creation and the meAsProxy fields. Use the linked Spring Boot 2.4 migration guidance to identify replacements. Done means deprecated configuration is removed or replaced, each service serves an APIML favicon, compatibility is verified, and circular references no longer require the setting.