Limit the set of tests run in appveyor (#2989)

* Limit the set of tests run in appveyor

The py37 job run in appveyor isn't meant to actually count, it's
there so appveyor won't leave a pending job sitting in the github
checks list while we have it configured as a wheel building backup
for azure. Right now this job is failing and leaving a red x on commits
(which is at least as bad as leaving patches status as pending) because
of a new pulse test that is sensitive to subtle floating point type
differences between environments. To avoid the bad optics of a red x on
jobs we don't care about this commit switches the set of tests we run in
this job we only configured to make it easy to ignore to just a single
test module that is unlikely to fail unless it fails on all
environments.

* Don't run anything

appveyor.yml

@@ -70,16 +70,8 @@ install:
           https://ci.appveyor.com/api/projects/$env:APPVEYOR_ACCOUNT_NAME/$env:APPVEYOR_PROJECT_SLUG/history?recordsNumber=50).builds | `
           Where-Object pullRequestId -eq $env:APPVEYOR_PULL_REQUEST_NUMBER)[0].buildNumber) { `
             throw "There are newer queued builds for this pull request, failing early." }
-    - "%PYTHON%\\python.exe -m venv venv"
-    - venv\Scripts\activate.bat
-    - pip.exe install -U -r requirements.txt -r requirements-dev.txt -c constraints.txt
-    - pip.exe install -e .
-    - pip.exe install "qiskit-ibmq-provider" -c constraints.txt
-    - python setup.py build_ext --inplace
-
 test_script:
-    - stestr run
-    - stestr last --subunit > test_results.subunit
+    - true
 
 on_failure:
   - appveyor PushArtifact wheelhouse\*whl