Cleaning unused parts of HistoryTrackerInterface

[john-science]

What is the change? Why is it being made?

Cleaning out unused code in the HistoryTrackerInterface:

• self.time - Entirely unused in ARMI, or anywhere I can find downstream.
• self.fullCoreLocations - Entirely unused in ARMI, or anywhere I can find downstream.
• self.xsHistory - For the past 6 years that ARMI has existed, I can find no code that has ever WRITTEN TO this variable. I have also checked out, internal, projects that use this code, and have never seen this WRITTEN TO.
  • As such, there is a reporting tool that plots this, and every example I can find of this plot having been made in the wild... the plot is empty of data, because this is empty. So I remove the lame plot as well.
• def _getBlockHistoryFileName(self): - Unused.
• def _getLocationHistoryFileName(self): - Unused.
• def filterTimeIndices(self): - Unused.

NOTE: I have tested this downstream to the best of my ability, and every test and run I could do downstream passes. I am fairly confident that these three class attributes are unused.

(Extra: I also cleaned up the docstrings and f-strings in this file. Sorry, I can't help myself.)

SCR Information

Change Type: trivial

One-Sentence Rationale: The HistoryTrackerInterface has not gotten a lot of love in the past few years, so this is the start of an effort to clean it up and simplify it.

One-line Impact on Requirements: NA

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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 documentation is still up-to-date in the doc folder.
• The code style follows good practices.
• The dependencies are still up-to-date in pyproject.toml.