Fix/clang format issues

Issue/feature addressed

Some clang-format errors were accidentally introduced in MR !1342 (merged).

Proposed solution

Fix the errors.

Implementation

clang-format-11 run on the affected files.

Tests

Suggested reviewers

Notes

• I do not think it is necessary to update the CHANGELOG for this one.
• Requires rebase on master after merge of !1656 (merged)

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).