Fix hdf5 partition for Parareal

Issue/feature addressed

The previous implementation of the hdf5 mesh partition does not have any provision for Parallel-in-Time partitioning. This MR fix the problem and allow the use of multiple processors in time.

Proposed solution

Use GetSpaceComm() communicator when relevant.

Implementation

Tests

Suggested reviewers

Please suggest any people who would be appropriate to review your code.

Notes

Please add any other information that could be useful for reviewers.

Checklist

• Functions and classes, or changes to them, are documented.
• [ ] User guide/documentation is updated.
• Changelog is updated.
• Suitable tests added for new functionality.
• Contributed code is correctly formatted. (See the contributing guidelines).
• [ ] License added to any new files.
• No extraneous files have been added (e.g. compiler output or test data files).