CppEditor: Simplify CppCodeModelSettings setup

Change-Id: Ie6849caf8ded2c0901a9d2daeda6a1f81b68ed72
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/cppeditor/cppcodemodelsettings.cpp

@@ -68,6 +68,11 @@ static FilePath fallbackClangdFilePath()
     return Environment::systemEnvironment().searchInPath("clangd");
 }
 
+CppCodeModelSettings::CppCodeModelSettings()
+{
+    fromSettings(Core::ICore::settings());
+}
+
 void CppCodeModelSettings::fromSettings(QtcSettings *s)
 {
     s->beginGroup(Constants::CPPEDITOR_SETTINGSGROUP);
@@ -594,4 +599,10 @@ int ClangdSettings::Data::defaultCompletionResults()
     return ok ? userValue : 100;
 }
 
+CppCodeModelSettings &cppCodeModelSettings()
+{
+    static CppCodeModelSettings theCppCodeModelSettings;
+    return theCppCodeModelSettings;
+}
+
 } // namespace CppEditor