[dynamic plugins]: make it clear why we send events about unloading core plugin
[dynamic plugins]: make it clear why we send events about unloading core plugin

GitOrigin-RevId: d33673b220e52df6f37fb062c40385b78b5a97b9
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