Python: avoid cleanip in destructor of Instance. It doesn't work right on Linux.

ApplicationCode/GrpcInterface/Python/rips/Instance.py

@@ -106,7 +106,3 @@ class Instance:
     
         path = os.getcwd()
         self.commands.setStartDir(path=path)
-
-    def  __del__(self):
-        if self.launched:
-            self.app.exit()

ApplicationCode/GrpcInterface/Python/tests/conftest.py

@@ -33,3 +33,6 @@ def pytest_configure(config):
     if not _rips_instance:
         print("Need a valid ResInsight executable to launch tests")
         exit(0)
+
+def pytest_unconfigure():
+    _rips_instance.app.exit()