Fix slowness of loading large experiment lists due to pkg_resources->importlib change

[jbeilstenedmands]

Fixes #657

[codecov]

Codecov Report

Merging #658 (cfb50e5) into main (9657a16) will increase coverage by 0.03%.
The diff coverage is 80.00%.

❗ Current head cfb50e5 differs from pull request most recent head 33fe178. Consider uploading reports for the commit 33fe178 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #658      +/-   ##
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+ Coverage   37.96%   37.99%   +0.03%     
==========================================
  Files         182      182              
  Lines       15817    15825       +8     
  Branches     3037     3037              
==========================================
+ Hits         6005     6013       +8     
  Misses       9244     9244              
  Partials      568      568              

[ndevenish]

So, after digging into this, this seems to be an issue to do with either:

• Python 3.10 (goes away on 3.11)
• tbx-distribution layout (goes away on 3.10 with CMake bootstrap, where entry_points are installed into site-packages)

There are change notes on python 3.11 that performance regressions were addressed; I don't know why the backport didn't fix these.

So, this seems pretty reasonable.