Add mandatory tags for rabbitmq integrations

[rarguelloF]

What does this PR do?

Adds the mandatory tag messaging.rabbitmq.routing_key for rabbitmq integrations (only sneakers).

Motivation

Unify span tags across tracers.

Additional Notes

How to test the change?

Updated unit tests.

[codecov-commenter]

Codecov Report

Merging #2613 (fd5b865) into master (e078c25) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2613      +/-   ##
==========================================
- Coverage   98.02%   98.02%   -0.01%     
==========================================
  Files        1148     1148              
  Lines       62357    62357              
  Branches     2806     2806              
==========================================
- Hits        61126    61125       -1     
- Misses       1231     1232       +1     

Impacted Files	Coverage Δ
lib/datadog/tracing/contrib/ext.rb	100.00% <100.00%> (ø)
lib/datadog/tracing/contrib/sneakers/tracer.rb	100.00% <100.00%> (ø)
...ec/datadog/tracing/contrib/sneakers/tracer_spec.rb	100.00% <100.00%> (ø)
lib/datadog/core/diagnostics/environment_logger.rb	97.69% <0.00%> (-1.57%)	⬇️
...ng/contrib/active_support/cache/instrumentation.rb	86.30% <0.00%> (+0.09%)	⬆️
...ec/datadog/tracing/contrib/sidekiq/patcher_spec.rb	100.00% <0.00%> (+4.00%)	⬆️

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[zarirhamza]

LGTM