✨ [Docker] Migrated from rockylinux:8-minimal to rockylinux:9-minimal base image

[Coduz]

This PR changes the base image used to build our java-base image for Docker containers

Main scope of this change is to move to a more recent base image and also improve Docker image footprint.

Container	Size Rockylinux 8-minimal	Size Rockylinux 9-minimal
kapua/java-base	640MB	610 MB
kapua/jetty-base	689 MB	659 MB
kapua/kapua-sql	645 MB	615 MB
kapua/kapua-events-broker	897 MB	867 MB
kapua/kapua-api	955 MB	925 MB
kapua/kapua-job-engine	922 MB	892 MB
kapua/kapua-broker-artemis	992 MB	962 MB
kapua/kapua-service-authentication	766 MB	636 MB
kapua/kapua-consumer-lifecycle	780 MB	750 MB
kapua/kapua-consumer-telemetry	771 MB	741 MB

The java-base image shrinks of 30 MB, which are saved for each of the Docker container that are using it (all of them).

Moving to 9-minimal also decreases the number of vulnerabilities for our Docker images.

Related Issue
None

Description of the solution adopted
Updated the base image reference from 8-minimal to 9-minimal

Screenshots
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Any side note on the changes made
None