Remove the old SPA context which we no longer use

[stephen-riggs]

Also removes some environment parameters which appear to never be set.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 27.09%. Comparing base (0f59d2e) to head (11977b4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #453      +/-   ##
==========================================
+ Coverage   27.06%   27.09%   +0.03%     
==========================================
  Files          76       76              
  Lines       10191    10046     -145     
  Branches     1345     1319      -26     
==========================================
- Hits         2758     2722      -36     
+ Misses       7345     7232     -113     
- Partials       88       92       +4