Remove qmake build files

Removes qmake as a build system for building Qt Creator itself.
Keep them for some tests that are not completely moved to CMake yet.

Change-Id: I846c6ef65626b6dfae6375fdc85d00677aa8c2fb
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/marketplace/marketplace.pro

@@ -1,16 +0,0 @@
-TARGET = Marketplace
-TEMPLATE = lib
-QT += network
-
-include(../../qtcreatorplugin.pri)
-
-DEFINES += MARKETPLACE_LIBRARY
-
-SOURCES += \
-    productlistmodel.cpp \
-    qtmarketplacewelcomepage.cpp
-
-HEADERS += \
-    marketplaceplugin.h \
-    productlistmodel.h \
-    qtmarketplacewelcomepage.h

src/plugins/marketplace/marketplace_dependencies.pri

@@ -1,7 +0,0 @@
-QTC_PLUGIN_NAME = Marketplace
-
-QTC_PLUGIN_DEPENDS += \
-    coreplugin
-
-QTC_LIB_DEPENDS += \
-    utils