MLPAB-2318: Send attorney opt out to lpa-store

[acsauk]

Purpose

Fixes MLPAB-2318

Also includes a small fix to some mocks. As we're dropping mocks before generating them I encountered a couple of issues:

• We didn't have an interface for sessions.CookieStore so weren't regenerating it
• We weren't using the mock for LpaResolvingService

(and Dockerfile changes to fix a casing mismatch warning)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.08%. Comparing base (455b7de) to head (f69b312).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1419   +/-   ##
=======================================
  Coverage   95.08%   95.08%           
=======================================
  Files         251      251           
  Lines       11201    11209    +8     
=======================================
+ Hits        10650    10658    +8     
  Misses        394      394           
  Partials      157      157           

Flag	Coverage Δ
unittests	95.08% <100.00%> (+<0.01%)	⬆️

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