Merge micromamba files

[furtib]

Describe the task

We have 2 different micromamba files, one for CI and one, for local use.
We should merge these two.

Idea:
Currently, the micromamba init script replaces the @BAZEL_VERSION@ decorators with the desired version number.
We could replace these in a CI workflow.
Things to look out for:

• Do not break caching on CI.

Scope

• Micromamba environments merged

Definition of Done

• Only 1 Micromamba environment file exists