Fix message when writer is NoOp

[xgouchet]

What does this PR do?

This avoids misleading logs when a RUM session is expired and the writer becomes no op (it returns false on write).

Motivation

Avoid noise and misleading noise in logcat for customer, and provide a more relevant explanation

[0xnm]

nice catch! I added a suggestion.

[0xnm]

suggestion: we probably should also call onSuccess/onError here (don't know which one makes more sense), because at least for the RumViewScope until sum(pending) == 0 it won't be marked as complete and thus garbage collected. We may have the case when there is NoOpDataWriter here and RUM pipeline working if session is not tracked, I believe.

[codecov-commenter]

Codecov Report

Merging #1963 (133f4eb) into develop (a107d7c) will increase coverage by 0.04%.
Report is 6 commits behind head on develop.
The diff coverage is 86.67%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1963      +/-   ##
===========================================
+ Coverage    83.24%   83.29%   +0.04%     
===========================================
  Files          489      489              
  Lines        17857    17837      -20     
  Branches      2661     2664       +3     
===========================================
- Hits         14865    14856       -9     
+ Misses        2264     2245      -19     
- Partials       728      736       +8     

Files	Coverage Δ
...kotlin/com/datadog/android/rum/utils/SdkCoreExt.kt	95.56% <86.67%> (-1.88%)	⬇️

... and 36 files with indirect coverage changes