fix(analysis): explicitly set datadog aggregator to last only on v2

[alexef]

the field is required by the v2 API and we currently leave it empty string.

@zachaller you removed it in #3643 and that is fine. this PR will not add it back to the schema and not break the v1 API.

without this change and without aggregator set on a v2 metric, one gets:

received non 2xx response code: 400 {"errors":["Value of parameter
            'aggregator' should be any of these [None, 'avg', 'min', 'max',
            'sum', 'last', 'mean', 'area', 'l2norm', 'percentile', 'stddev']"]}

If we set it to None, according to datadog docs it will default to avg. According to rollouts docs, we should default to last (which makes sense for analysis)

https://docs.datadoghq.com/api/latest/metrics/#query-scalar-data-across-multiple-products

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this is a chore.
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.29%. Comparing base (4f1edbe) to head (c9a5326).
Report is 95 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3730      +/-   ##
==========================================
+ Coverage   80.27%   80.29%   +0.02%     
==========================================
  Files         156      156              
  Lines       17964    18023      +59     
==========================================
+ Hits        14420    14472      +52     
- Misses       2631     2637       +6     
- Partials      913      914       +1     

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[github-actions]

Go Published Test Results

2 171 tests   2 171 ✅  2m 54s ⏱️
  119 suites      0 💤
    1 files        0 ❌

Results for commit c9a5326.

♻️ This comment has been updated with latest results.

[github-actions]

E2E Tests Published Test Results

  4 files    4 suites   3h 23m 42s ⏱️
111 tests 105 ✅  6 💤 0 ❌
444 runs  420 ✅ 24 💤 0 ❌

Results for commit c9a5326.

[mickeyrouash]

@alexef I also experience it , is there a way to workaround it and still using Datadog V2 ?

[alexef]

@mickeyrouash yes, the workaround is adding aggregator: last to your analysis template (this will now do it implicitely)

[aguiraorodriguez]

Is this PR addressing #3707 ?

[alexef]

@aguiraorodriguez exactly, that issue should be fixed by this PR, as part of 1.7.2 release