Try doing retries in test_ext_ai_indexing_02 (#8325)

The more general fix is that assert_query_result ought to do retries
when not in a transaction, of course, but let's try to get this
release out.

This is a forward-port from something already on the 6.x branch.

tests/test_ext_ai.py

@@ -20,6 +20,8 @@
 import pathlib
 import unittest
 
+import edgedb
+
 from edb.server.protocol import ai_ext
 from edb.testbase import http as tb
 
@@ -255,20 +257,28 @@ async def test_ext_ai_indexing_02(self):
             # updating an object should make it disappear from results.
             # (the read is done in the same tx, so there is no possible
             # race where the worker picks it up before the read)
-            await self.assert_query_result(
-                """
-                update Stuff filter .content like '%Earth'
-                set { content2 := ' are often grey' };
-                """ + qry,
-                [
-                    {
-                        'content': 'Skies on Mars',
-                        'content2': ' are red',
-                        'distance': 0.4284523933505918,
-                    },
-                ],
-                variables=dict(qv=qv),
-            )
+            async for tr in self.try_until_succeeds(
+                ignore=(
+                    edgedb.TransactionConflictError,
+                    edgedb.TransactionSerializationError,
+                ),
+                timeout=30.0,
+            ):
+                async with tr:
+                    await self.assert_query_result(
+                        """
+                        update Stuff filter .content like '%Earth'
+                        set { content2 := ' are often grey' };
+                        """ + qry,
+                        [
+                            {
+                                'content': 'Skies on Mars',
+                                'content2': ' are red',
+                                'distance': 0.4284523933505918,
+                            },
+                        ],
+                        variables=dict(qv=qv),
+                    )
 
         finally:
             await self.con.execute('''