add the time_format field to qlog common_fields

[marten-seemann]

qvis is complaining about this:

[codecov]

Codecov Report

Merging #3038 (7e59a09) into master (0b97ae5) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3038      +/-   ##
==========================================
- Coverage   86.05%   86.04%   -0.01%     
==========================================
  Files         135      135              
  Lines        9472     9473       +1     
==========================================
  Hits         8151     8151              
- Misses        961      962       +1     
  Partials      360      360              

Impacted Files	Coverage Δ
qlog/trace.go	90.91% <100.00%> (+0.43%)	⬆️
qlog/qlog.go	90.87% <0.00%> (-0.38%)	⬇️

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