Optimize response body length reporting in OkHttp instrumentation

[0xnm]

What does this PR do?

This PR optimizes the way we are reporting response body length in OkHttp instrumentation.

We first try to get content length from response body as-is, and if it didn't work, we try to call peekBody. The explanation to that is related to the way OkHttp works: the following doc states, that OkHttp will remove Content-Length header (and make contentLength() return -1) if transparent compression is used. This means that if body.contentLength returns positive value, then we are good already, and if it is not, we may try to call peekBody which will apply decompression and load a decompressed body in memory.

Another benefit is that now we can report body length more than 1MB, because peekBody was limited by 1MB and if there is no need to call it, we may report full body length.

Motivation

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Additional Notes

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Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[codecov-commenter]

Codecov Report

Merging #1790 (c42c0c2) into develop (9eefcc4) will decrease coverage by 0.21%.
The diff coverage is 83.33%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1790      +/-   ##
===========================================
- Coverage    83.64%   83.43%   -0.21%     
===========================================
  Files          466      466              
  Lines        16368    16347      -21     
  Branches      2451     2449       -2     
===========================================
- Hits         13691    13639      -52     
- Misses        2023     2042      +19     
- Partials       654      666      +12     

Files	Coverage Δ
...n/com/datadog/android/okhttp/DatadogInterceptor.kt	72.92% <83.33%> (+0.38%)	⬆️

... and 23 files with indirect coverage changes