[tests] dispose light project before checking references to extension objects in testDynamicExtensions
[tests] dispose light project before checking references to extension objects in testDynamicExtensions

Light project instance stored by last executed light test may contain references to some extensions. The code which cleans such references when extension point is unregistered doesn't process light project because it isn't included into open projects.

GitOrigin-RevId: 31a465ca8384544100bc447defc3e07512f86db5
allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community,allotria/intellij-community