mavsdk_tests: leave tests backwards compatible but enable SIH

This reverts some of the changes to keep runners of classic Gazebo in
there but leave it optional, so we can still use it if required.

test/mavsdk_tests/integration_test_runner/process_helper.py

@@ -168,7 +168,7 @@ class Px4Runner(Runner):
                 os.path.join(workspace_dir, "test_data"),
                 "-d"
             ]
-        self.env["PX4_SIM_MODEL"] = "sihsim_quadx"
+        self.env["PX4_SIM_MODEL"] = model
         self.env["PX4_SIM_SPEED_FACTOR"] = str(speed_factor)
         self.debugger = debugger
         self.clear_rootfs()

test/mavsdk_tests/integration_test_runner/test_runner.py

@@ -302,7 +302,7 @@ class Tester:
         self.active_runners = []
 
         if self.config['mode'] == 'sitl':
-            if self.config['simulator'] == 'gazebo':
+            if self.config.get('simulator') == 'gazebo':
                 # Use RegEx to extract worldname.world from case name
                 match = re.search(r'\((.*?\.world)\)', case)
                 if match:
@@ -310,24 +310,52 @@ class Tester:
                 else:
                     world_name = 'empty.world'
 
-                # We must start the PX4 instance at the end, as starting
-                # it in the beginning, then connecting Gazebo server freaks
-                # out the PX4 (it needs to have data coming in when started),
-                # and can lead to EKF to freak out, or the instance itself
-                # to die unexpectedly.
-                px4_runner = ph.Px4Runner(
+                gzserver_runner = ph.GzserverRunner(
                     os.getcwd(),
                     log_dir,
                     test['model'],
                     case,
                     self.get_max_speed_factor(test),
-                    self.debugger,
                     self.verbose,
                     self.build_dir,
-                    self.tester_interface.rootfs_base_dirname())
-                for env_key in test.get('env', []):
-                    px4_runner.env[env_key] = str(test['env'][env_key])
-                self.active_runners.append(px4_runner)
+                    world_name)
+                self.active_runners.append(gzserver_runner)
+
+                gzmodelspawn_runner = ph.GzmodelspawnRunner(
+                    os.getcwd(),
+                    log_dir,
+                    test['model'],
+                    case,
+                    self.verbose,
+                    self.build_dir)
+                self.active_runners.append(gzmodelspawn_runner)
+
+                if self.gui:
+                    gzclient_runner = ph.GzclientRunner(
+                        os.getcwd(),
+                        log_dir,
+                        test['model'],
+                        case,
+                        self.verbose)
+                    self.active_runners.append(gzclient_runner)
+
+            # Determine PX4_SIM_MODEL using model_prefix from config
+            model_prefix = self.config.get('model_prefix', '')
+            px4_model = model_prefix + test['model']
+
+            px4_runner = ph.Px4Runner(
+                os.getcwd(),
+                log_dir,
+                px4_model,
+                case,
+                self.get_max_speed_factor(test),
+                self.debugger,
+                self.verbose,
+                self.build_dir,
+                self.tester_interface.rootfs_base_dirname())
+            for env_key in test.get('env', []):
+                px4_runner.env[env_key] = str(test['env'][env_key])
+            self.active_runners.append(px4_runner)
 
         self.active_runners.append(self.tester_interface.create_test_runner(
             os.getcwd(),