[Java] Fix POM

[ldematte]

As reported in #1090, we are producing a "broken" "jar with dependecies" today: the Jar contains extra files that make it impossible to consume from a modularized application, as it breaks the module definition.

This PR fixes this by:

• removing spotless as a dependency: adding it as a dependency is not needed, as spotless is used at build time
• removing the jar-with-dependency build task: we don't need it, as we don't have dependencies today. If we have in the future, we can re-introduce it, with a better handling of the merge process
• change the build script to install in the local maven repository the "regular" jar produced by the build process

EDIT: after review, we decided to revert the removal of the task creating jar-with-dependency, as we might need it in the future (will need fixing anyway, but we can defer that until we need it).

Closes #1090

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[ldematte]

@mythrocks I have updated the PR to keep the jar-with-dependencies

[mythrocks]

/ok to test a132570

[mythrocks]

The CI builds should be fixed once #1114 is resolved.

[benfred]

/ok to test f20d41a

[mythrocks]

Will prioritize #1034 first, to address the build failures.

[mythrocks]

/ok to test d64157d

[mythrocks]

/merge

[mythrocks]

@KyleFromNVIDIA, could I please bother you for a packaging-owners review for this change?