Fix zarr.save for given path and multiple args arrays

[brokkoli71]

When save has an argument path=some/path/ and multiple arrays in args, the path resulted in some/path/some/path due to using the path argument twice while building the array path. This gets fixed in this PR

TODO:

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.rst
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)