CMake: omit configuration dropping on cache clear

Setting CMake configuration to the provided by the Kit, drops all users
settings to the default one. CMAKE_BUILD_TYPE too.

Change-Id: I8be556f553376273933872a74e47937df5a74f30
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakeprojectmanager.cpp

@@ -117,7 +117,6 @@ void CMakeManager::clearCMakeCache(Project *project)
     if (!bc)
         return;
 
-    bc->setCMakeConfiguration(CMakeConfigurationKitInformation::configuration(bc->target()->kit()));
     bc->buildDirManager()->clearCache();
 }