MLPAB-2321: Delete scheduled tasks when CANNOT_REGISTER lpa-updated event received

[acsauk]

Purpose

Fixes MLPAB-2321

[acsauk]

Some things to think about with scheduled tasks going forward:

• Ignored tasks won't get rerun with the current implementation. How do we want to handle this going forward?
• Will we have a retention policy on handled tasks and/or tasks at a certain age? If not, it makes sense to give tasks linked to an LPA with cannot-register a handled (or something) status

[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 3 lines in your changes missing coverage. Please review.

Project coverage is 94.83%. Comparing base (b44d4ca) to head (1e13d5d).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/event-received/lpastore_event_handler.go	83.33%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1640      +/-   ##
==========================================
+ Coverage   94.35%   94.83%   +0.48%     
==========================================
  Files         283      282       -1     
  Lines       15581    15551      -30     
==========================================
+ Hits        14701    14748      +47     
+ Misses        709      632      -77     
  Partials      171      171              

Flag	Coverage Δ
unittests	94.83% <96.55%> (+0.48%)	⬆️

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[hawx]

I don't think there is any point having uid again, we should be able to trust the previous query

[hawx]

so could use DeleteKeys

[acsauk]

I'd originally used DeleteKeys but then switched to this. I know the likelihood of getting exactly the same timestamp + action type is low but as the keys aren't unique I wanted a failsafe there to be sure we weren't deleting unintended events. If you're comfortable with that risk feel free to drop this while I'm out and just rely on the keys 👍

[hawx]

every (PK, SK) is unique, so it won't be an issue. I have spotted Put doesn't use Create, so it would currently overwrite an existing scheduled event, I'm going to change that