ProjectExplorer: fix Interpreter::changed emits

Only emit changed if the current interpreter changes.
This is more in line with the other aspects.

This fixes the pyside detection since the changed signal was not
emitted in all relevant code paths.

Change-Id: I53409b17f260b35914e39de894b48d7bd1ce27c0
Reviewed-by: hjk <hjk@qt.io>

src/plugins/python/pythonrunconfiguration.cpp

@@ -127,7 +127,6 @@ public:
     {
         connect(q, &InterpreterAspect::changed,
                 this, &PythonInterpreterAspectPrivate::currentInterpreterChanged);
-        currentInterpreterChanged();
 
         connect(PySideInstaller::instance(), &PySideInstaller::pySideInstalled, this,
                 [this](const FilePath &python) {