McuSupport: remove cmake mapper

Starting with Qt For MCUs 2.0, environment variables are not
used to track dependencies any more, but cmake variables are.
Due to time constraints, we implemented a env-to-cmake mapper
to cover that gap at the moment. This patch removes that hack
and implements tracking dependencies through cmake variables.

Task-number: QTCREATORBUG-26904
Change-Id: Id8553a764d212d9b12e4adc54fc56233bfeb9a5b
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mcusupport/mcusupportoptionspage.cpp

@@ -307,7 +307,7 @@ void McuSupportOptionsWidget::apply()
 
     if (pathsChanged) {
         m_options.checkUpgradeableKits();
-        McuKitManager::fixKitsDependencies();
+        McuKitManager::updatePathsInExistingKits();
     }
 }
 
@@ -317,7 +317,7 @@ void McuSupportOptionsWidget::populateMcuTargetsComboBox()
     m_mcuTargetsComboBox->clear();
     m_mcuTargetsComboBox->addItems(
         Utils::transform<QStringList>(m_options.sdkRepository.mcuTargets,
-                                      [](McuTarget *t) { return McuKitManager::kitName(t); }));
+                                      [](McuTarget *t) { return McuKitManager::generateKitNameFromTarget(t); }));
     updateStatus();
 }