Remove dead code from the TPR parser

[jbarnoud]

Fixes #3515

Remove dead code as promised in #3514

PR Checklist

- [ ] Tests?
- [ ] Docs?
- [ ] CHANGELOG updated?

• Issue raised/referenced?

[IAlibay]

yeah I guess the best option is just to remove it - it's too bad since it's quite informative, but at least it's in previous versions so we can mine it from there as needed

[codecov]

Codecov Report

Merging #3516 (af11f42) into develop (e482c39) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #3516   +/-   ##
========================================
  Coverage    94.06%   94.06%           
========================================
  Files          176      176           
  Lines        23284    23284           
  Branches      3303     3303           
========================================
  Hits         21903    21903           
  Misses        1335     1335           
  Partials        46       46           

Impacted Files	Coverage Δ
package/MDAnalysis/topology/TPRParser.py	95.16% <ø> (ø)
package/MDAnalysis/topology/tpr/utils.py	97.18% <ø> (ø)

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