Insignificant test for Ubuntu 20_04 in Coin configuration

It seems that QSR has inherited one test configuration from the Qt 5.

The Ubuntu 20_04 version has insignificant tests.

Links: 

QSR 2.0 RC4 Coin task:

http://coin/coin/integration/tqtc-boot2qt/qtsaferenderer/tasks/1680754036

Specific log instance (test)

http://coin/coin/logview/tqtc-boot2qt/qtsaferenderer/070f104ef226fca2982a0fbd9401bd0df39f3077/LinuxUbuntu_20_04x86_64LinuxUbuntu_20_04x86_64GCCqtci-linux-Ubuntu-20.04-x86_64-50-1ecb54Documentation_InsignificantTests_OutOfSourceBuild/508a5855cfe4cf7c0a70266251826c78697d8d3b/test_1680754042

Reference from Qt 5

http://coin/coin/integration/qt/tqtc-qt5/tasks/1681071980

There are three configs in the Qt 5 side for Ubuntu 20_04 and there are both normal tests and insignificant tests.

Perhaps QSR should have Ubuntu 20_04 config in the Coin that does not have the insignificant test feature.

Be it tailored config (modify the existing one) or add another with such config.