Travis now sometimes fails with following output (at codecov)

No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.

Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received

The build has been terminated

This PR reverted parts of #5609, because of #5609 (comment)

CodeCov should really fail if test coverage decreases. This fosters awareness to add tests.

CodeCov should not fail because of timeouts during tests. At least not if that happens often (as it is currently the case)

I assume the timeout is because some databases started and stopped in parallel and maybe that eats too much cpu, ram, ...

Also fails here: https://travis-ci.org/JabRef/jabref/builds/615330243?utm_source=github_status&utm_medium=notification

Flagged as devcall with the hope, we have time to talk about it today.

Decision: We keep as is and force ourselves to fix the DBMS tests. - Maybe move to GitHub actions for that, too.

Issue tracking this: #5602