Since you have a single released version product one thing to consider would be keeping the Develop branch or not:
keeping it would have the advantage that at any moment you can bring in a hotfix in master even if Develop isn't stable enough for a merge into master. But this means you'd need to have 2 focus points instead of a single one - both branches ...
If you check the Git plugin documentation, you can see that there is a GIT_BRANCH environment variable that you can use in your pipeline.
GIT_BRANCH - Name of the remote repository (defaults to origin),
followed by name of the branch currently being used,
e.g. "origin/master" or "origin/foo"
So, in your pipeline:
stage('Push to ...