qtdeclarative tests fail when building tests ahead of time

Then coin is configured to build tests separately right after the module build and then deploy test binaries, the declarative tests, in particular qqmlmoduleplugin fails:

https://testresults.qt.io/coin/integration/qt/qtdeclarative/tasks/1571900911

The build log of that integration shows that the tests are compiled during the build phase, but later during the test phase, the build kicks in again. That eventually fails.