Update maven-agent, springboot & spock-geb quickstarter

[renedupont]

This PR introduces the below changes:

spock-geb qs:

• raises dependencies and gradle version

be-springboot qs:

• raises springboot + dependencies, ubi image and gradle version
• removes restdocs as dependency
• fixes param names of spring initializr call
• updates removed jacoco xml setting in build.gradle (xml.enabled was removed in gradle 8 in favor of xml.required)

maven-agent:

• adds temporary java17 switch bugfix in Dockerfile
• removes gradle and maven installation (due to usage of wrapper in projects) while keeping proxy and nexus settings for them

Note: Removing gradle and maven from the agent is a breaking change for projects that don't use either gradle or maven wrapper in their projects. The fix in these cases would be to start using the wrapper approach. If adapting is not possible right away, the old maven agent could be used via ref.

closes #878

[BraisVQ]

Thanks for the contribution @renedupont
I will try to test it to ensure retrocompatibility and prepare internal documentatio in case maven users still need to use it

[BraisVQ]

@renedupont , open question. Should the agent be renamed ?
Currently its name is maven but we have removed maven from it.

[renedupont]

Yes, what about just java-agent, or even better jdk-agent?

[BraisVQ]

Jdk makes more sense.
I will check internally first but there should not be any issue changing the agent name.

Also I have tested this:

• Provision both quickstarters with new agent
• Test maven wrapper approach
• Provision both qs with old version of the agent and qs, then build them with new agent successfully (without changes).

[BraisVQ]

@renedupont , we have the ok for the name change.

[BraisVQ]

Tested current build, provision and retrocompatibility with old QS version successfully.
The use of Maven wrapper also works as expected for the use cases that needs maven