DEBUG-2334 Set duration to 0 for DI line probes

[p-datadog]

What does this PR do?
This PR changes the probe notification builder to set duration to 0 in the generated payload if it was not supplied by the caller.

Motivation:
Line probes do not have a meaningful duration, however schema validation in system tests demands a numeric value.

Follow the behavior of other tracers and send 0 instead of nil in this case.

Change log entry
None

Additional Notes:

This PR also includes additional assertions in the unit test for probe notification builder to make that test in general way more useful. Some of these assertions already exist in integration tests but here they are closer to the code.

How to test the change?
Tested by system tests (DataDog/system-tests#3516) and by the unit tests in this PR.

[TonyCTHsu]

Default 0 make sense to me. Can remove other nil check from the caller.

I assumed to input duration can be nil or Float, otherwise, nil.to_i can convert to 0 as well.

[p-datadog]

It is a number which is a float per https://json-schema.org/understanding-json-schema/reference/numeric: https://github.com/DataDog/system-tests/blob/main/utils/interfaces/schemas/library/debugger/v1/input-request.json#L9

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.61017% with 2 lines in your changes missing coverage. Please review.

Project coverage is 97.78%. Comparing base (722f487) to head (71c1ea4).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
spec/datadog/di/probe_notification_builder_spec.rb	96.49%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4134      +/-   ##
==========================================
- Coverage   97.79%   97.78%   -0.01%     
==========================================
  Files        1350     1350              
  Lines       81276    81322      +46     
  Branches     4107     4107              
==========================================
+ Hits        79481    79519      +38     
- Misses       1795     1803       +8     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-11-20 21:56:04

Comparing candidate commit 71c1ea4 in PR branch di-duration with baseline commit ec23c49 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.