Fix hash log_tags warning

[TonyCTHsu]

What does this PR do?

Skip warning for log injection configuration when Semantic Logger's named tags override Rails built-in config.log_tags with a hash value

[codecov-commenter]

Codecov Report

Merging #3022 (bec63ef) into master (6031043) will increase coverage by 0.03%.
Report is 11 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3022      +/-   ##
==========================================
+ Coverage   98.08%   98.12%   +0.03%     
==========================================
  Files        1317     1322       +5     
  Lines       74362    74622     +260     
  Branches     3402     3403       +1     
==========================================
+ Hits        72941    73222     +281     
+ Misses       1421     1400      -21     

Files Changed	Coverage Δ
lib/datadog/tracing/contrib.rb	100.00% <100.00%> (ø)
lib/datadog/tracing/contrib/rails/log_injection.rb	100.00% <100.00%> (ø)
lib/datadog/tracing/contrib/rails/patcher.rb	100.00% <100.00%> (ø)
...atadog/tracing/contrib/rails/log_injection_spec.rb	100.00% <100.00%> (ø)
.../datadog/tracing/contrib/suite/integration_spec.rb	100.00% <100.00%> (ø)
spec/datadog/tracing/contrib_spec.rb	100.00% <100.00%> (ø)

... and 8 files with indirect coverage changes

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