Remove oidc-implicit-flow (Follow-up from "Add the GFZ stages to the UFZ CI")

The following discussion from !223 (merged) should be addressed:

• @kotyba.alhaj-taha started a discussion: (+1 comment)

  The oidcdebugger-implicit-flow should be removed it was just for testing. So we will only have one aud therefore i see no need for that.