Remove time estimation for Parareal and PFASST

Issue/feature addressed

Time estimators have been used during the development of Parareal and PFASST. However, those estimators can be inaccurate for implicit time-stepping using iterative solvers. The time estimators have been removed in favor of actual time measurements.

Proposed solution

Implementation

Tests

Suggested reviewers

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

Notes

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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).