Remove ToolChain::suggestedDebugger()

And inline it in AndroidConfigurations, which is the only place that
made use of suggestedDebugger()

Change-Id: I87f135b5d115adb7e46b0f009c5853221e9a3daa
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/toolchain.cpp

@@ -169,11 +169,6 @@ QStringList ToolChain::suggestedMkspecList() const
     return {};
 }
 
-Utils::FilePath ToolChain::suggestedDebugger() const
-{
-    return ToolChainManager::defaultDebugger(targetAbi());
-}
-
 Core::Id ToolChain::typeId() const
 {
     return d->m_typeId;