Update GitHub Actions

[FrankSchnicke]

Due to the migration, some actions do not work anymore

[FrankSchnicke]

Currently, we have three actions:

• Deploy to maven central: Is obsolete due to mandatory Jenkins usage --> Delete
• Deploy to java Model: Is still needed. However, in the current state, it is still referencing the admin shell io packages --> Update
• Run Tests: is still needed. Most likely an update to also cover the main branch is sufficient.