remove volatile tests

Some tests relying on timings and external network resources were not
reliable and occasionally made builds on Travis fail.
minor #11603 remove volatile tests (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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remove volatile tests

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | part of #11588
| License       | MIT
| Doc PR        |

Commits
-------

24fb66d remove volatile tests