Enable test coverage check (#126)

In this PR we are enabling test coverage checks, which will ensure that
we maintain a high bar of test coverage.

Also in this PR, we are removing the "benchmarking" option, as we do not
currently have any benchmarks enabled:
https://github.com/aws-observability/aws-otel-python-instrumentation/actions/runs/8423785726/job/23066213144#step:4:627

Current test coverage:   1427 statements, 95 missed, 93.34% coverage

Regarding `{envsitepackagesdir}`, please see
https://stackoverflow.com/questions/58696476/tox-0-coverage

Testing:
* First raised the PR with 99% test coverage and workflows failed:
[link](https://github.com/aws-observability/aws-otel-python-instrumentation/actions/runs/8456289567/job/23165730029?pr=126)
* Then raised with 93% test coverage and workflows passed (see below)

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: thpierce

.coveragerc

@@ -0,0 +1,4 @@
+[report]
+include_namespace_packages = true
+fail_under = 93.00
+precision = 2

.github/actions/set_up/action.yml

@@ -41,4 +41,4 @@ runs:
     - name: Run unit tests/benchmarks with tox
       if: ${{ inputs.run_unit_tests == 'true' }}
       shell: bash
-      run: tox -f ${{ inputs.python_version }}-${{ inputs.package_name }} -- -ra --benchmark-json=${{ inputs.python_version }}-${{ inputs.package_name }}-${{ inputs.os }}-benchmark.json
+      run: tox -f ${{ inputs.python_version }}-${{ inputs.package_name }} -- -ra

tox.ini

@@ -14,7 +14,7 @@ envlist =
 deps =
   -c dev-requirements.txt
   test: pytest
-  test: pytest-benchmark
+  test: pytest-cov
 
 setenv =
   ; TODO: The two repos branches need manual updated over time, need to figure out a more sustainable solution.
@@ -37,7 +37,7 @@ commands_pre =
   aws-opentelemetry-distro: pip install {toxinidir}/aws-opentelemetry-distro
 
 commands =
-  test: pytest {posargs}
+  test: pytest --cov={envsitepackagesdir}/amazon --cov-config=../../.coveragerc {posargs}
 
 [testenv:spellcheck]
 basepython: python3