Removal of redundant tomography context code

[stephen-riggs]

This aims to fix the problems we see where late-started tomography sessions don't run alignment on some tomograms.

In that case the tilt series is never marked as completed by the client, so alignment cannot be run. I've removed a lot of unused or redundant code, and simplified the calls for checking tilt series completion. The completion check is now always run when a tilt is added.

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Project coverage is 28.50%. Comparing base (1791847) to head (aed113c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #381      +/-   ##
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+ Coverage   28.42%   28.50%   +0.08%     
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  Files          71       71              
  Lines        9537     9524      -13     
  Branches     1286     1273      -13     
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+ Hits         2711     2715       +4     
+ Misses       6730     6715      -15     
+ Partials       96       94       -2