Propose redesign of OMERO and Bio-Formats 5.0 CI jobs

This commit proposes to redesign the current architecture of the 5.0.x CI jobs
used for OMERO and Bio-Formats to match the 5.1.x CI jobs. Main changes are
the unification of the names across the 5.x branches, the systematic usage of
matrix jobs for OMERO and the separation between merging/pushing, artifact
building and server deployment into distinct jobs.

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--no-rebase