What does this PR do?

Fix coverage reporting for instrumentations.

Motivation

All this code was being generally ignored, artificially deflating our coverage numbers.

Codecov Report

Merging #1925 (88698fd) into master (3a75ffb) will increase coverage by 10.78%. The diff coverage is 88.88%.

:exclamation: Current head 88698fd differs from pull request most recent head 72d8913. Consider uploading reports for the commit 72d8913 to get more accurate results

@@             Coverage Diff             @@
##           master    #1925       +/-   ##
===========================================
+ Coverage   81.97%   92.75%   +10.78%     
===========================================
  Files         189      189               
  Lines        7671     7688       +17     
===========================================
+ Hits         6288     7131      +843     
+ Misses       1383      557      -826     

Impacted Files	Coverage Δ
...s/dd-trace/src/opentracing/propagation/text_map.js	97.03% <88.23%> (-1.29%)	:arrow_down:
packages/dd-trace/src/config.js	98.80% <100.00%> (+0.01%)	:arrow_up:
...datadog-instrumentations/src/helpers/instrument.js	96.49% <0.00%> (+7.01%)	:arrow_up:
packages/datadog-instrumentations/src/pino.js	25.00% <0.00%> (+11.53%)	:arrow_up:
packages/datadog-instrumentations/src/mongoose.js	93.33% <0.00%> (+60.00%)	:arrow_up:
packages/datadog-instrumentations/src/mocha.js	95.38% <0.00%> (+63.07%)	:arrow_up:
packages/datadog-instrumentations/src/amqplib.js	96.66% <0.00%> (+66.66%)	:arrow_up:
packages/datadog-instrumentations/src/ioredis.js	92.85% <0.00%> (+67.85%)	:arrow_up:
packages/datadog-instrumentations/src/pg.js	87.80% <0.00%> (+68.29%)	:arrow_up:
...ages/datadog-instrumentations/src/elasticsearch.js	88.88% <0.00%> (+68.88%)	:arrow_up:
... and 15 more

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@bengl is this PR safe to close? The relevant line in package.json now looks like this so I think the intent of this PR is already in master:

"test:plugins:ci": "yarn services && nyc --no-clean --include \"packages/datadog-instrumentations/src/@($(echo $PLUGINS)).js\" --include \"packages/datadog-instrumentations/src/@($(echo $PLUGINS))/**/*.js\" --include \"packages/datad...

I'll close this PR for now but we can consider reopening it in the future.