Do not start nodes when deleting a project

Project.delete() calls open() to rebuild the internal data structures
needed for cleanup. open() schedules start_all() when the project has
auto_start enabled, so deleting an auto-start project actually launched
every node process, allocating ports and consuming resources, only for
close() to kill them moments later.

open() now takes an auto_start argument (default True, so normal opens
are unchanged) and delete() passes auto_start=False.

Fixes #2784

gns3server/controller/project.py

@@ -917,7 +917,7 @@ class Project:
 
         if self._status != "opened":
             try:
-                await self.open()
+                await self.open(auto_start=False)
             except aiohttp.web.HTTPConflict as e:
                 # ignore missing images or other conflicts when deleting a project
                 log.warning(f"Conflict while deleting project: {e}")
@@ -998,9 +998,12 @@ class Project:
         return os.path.join(self.path, self._filename)
 
     @locking
-    async def open(self):
+    async def open(self, auto_start=True):
         """
         Load topology elements
+
+        :param auto_start: whether the nodes may be started when the project
+            has auto start enabled
         """
 
         if self._closing:
@@ -1114,7 +1117,7 @@ class Project:
         self._loading = False
         self.emit_controller_notification("project.opened", self.__json__())
         # Should we start the nodes when project is open
-        if self._auto_start:
+        if self._auto_start and auto_start:
             # Start all in the background without waiting for completion
             # we ignore errors because we want to let the user open
             # their project and fix it