[Bug] CI is not correctly caching the PR's -core version

[mwangggg]

 [INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------< io.cryostat:cryostat >------------------------
[INFO] Building cryostat 2.5.0-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] Downloading from github: https://maven.pkg.github.com/cryostatio/cryostat-core/io/cryostat/cryostat-core/2.26.0-SNAPSHOT/maven-metadata.xml
[INFO] Downloading from github: https://maven.pkg.github.com/cryostatio/cryostat-core/io/cryostat/cryostat-core/2.26.0-SNAPSHOT/cryostat-core-2.26.0-SNAPSHOT.pom
Warning:  The POM for io.cryostat:cryostat-core:jar:2.26.0-SNAPSHOT is missing, no dependency information available
[INFO] Downloading from github: https://maven.pkg.github.com/cryostatio/cryostat-core/io/cryostat/cryostat-core/2.26.0-SNAPSHOT/cryostat-core-2.26.0-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  1.642 s
[INFO] Finished at: 2023-12-04T18:45:26Z
[INFO] ------------------------------------------------------------------------
Error:  Failed to execute goal on project cryostat: Could not resolve dependencies for project io.cryostat:cryostat:jar:2.5.0-SNAPSHOT: Could not find artifact io.cryostat:cryostat-core:jar:2.26.0-SNAPSHOT in github (https://maven.pkg.github.com/cryostatio/cryostat-core) -> [Help 1]
Error:  
Error:  To see the full stack trace of the errors, re-run Maven with the -e switch.
Error:  Re-run Maven using the -X switch to enable full debug logging.
Error:  
Error:  For more information about the errors and possible solutions, please read the following articles:
Error:  [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/DependencyResolutionException
Error: Process completed with exit code 1.

CI failure looks like the builder is trying to use 2.26.0-SNAPSHOT for -core because that's the version in the pom.xml in this PR (since that's what is on main), but that is not a published version since we only publish actual releases, not snapshots.

I think the CI builder needs to build -core to test it, then upload that artifact. The "build Cryostat" task should then download that artifact again and re-install it into the local .m2 so that the Cryostat image build can find it and use it, so that the Cryostat build and tests use a -core artifact that is derived from the PR being tested.

Originally posted by @andrewazores in #314 (comment)

[mwangggg]

huh that didn't fix it...