feat(api): remove z safety margin from pipette movement check

[sanni-t]

Closes RESC-216

Overview

See the escalations ticket for more info.
Now that we use actual nozzle positions in movement conflict check, we shouldn't need to add such a big safety margin (10mm). We will prefer allowing the movement if it's in the realm of 'slight chance of collision'.

Review requests

Added an integration test. Feel free to throw some tests at it that check for collisions when moving to places where a pipette goes very close to a surrounding labware but falls just short of actually touching it.

Question: There is another way we can handle this and it's keeping the safety margin but making it low, like 2mm. Should we do that instead? See risk assessment for reason.

Risk assessment

Medium- low: there is a slight chance- due to equipment manufacturing tolerance that the pipette might touch/collide a deck item.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.57%. Comparing base (be34672) to head (5bee5d3).

Additional details and impacted files

@@                 Coverage Diff                  @@
##           chore_release-7.2.1   #14613   +/-   ##
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  Coverage                67.57%   67.57%           
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  Files                     2521     2521           
  Lines                    72237    72237           
  Branches                  9306     9306           
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  Hits                     48816    48816           
  Misses                   21226    21226           
  Partials                  2195     2195           

Flag	Coverage Δ
g-code-testing	92.43% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...i/src/opentrons/protocol_api/instrument_context.py	89.09% <ø> (ø)

[SyntaxColoring]

Makes sense, thanks.

I agree with removing the safety margin entirely until we can report these close shaves as nonblocking warnings.

[sanni-t]

Makes sense, thanks.

I agree with removing the safety margin entirely until we can report these close shaves as nonblocking warnings.

That's a good point about warnings!