Account for parent symmetry in component flux calculation

[mgjarrett]

What is the change?

Divide by the parent block's symmetry factor when calculating the volume fraction of a component for the integrated mg flux calculation.

Why is the change being made?

When getting the integrated flux for a component, the "volume fraction" of the component is calculated. This "volume fraction" is incorrect when the component's parent block has a symmetryFactor that is not unity, because the component getVolume() calculation does not account for the symmetry factor. To get the volume fraction correct, we have to divide by the symmetry factor.

Related to #2006 , but it doesn't totally resolve it. This just addresses one symptom of the component volume not respecting the symmetry factor. This does resolve #2059 .

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Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify any new/changed code.

• The code style follows good practices.
• The commit message(s) follow good practices.

• The release notes have been updated if necessary.
• The documentation is still up-to-date in the doc folder.
• The dependencies are still up-to-date in pyproject.toml.