Add test_explicit_timeline_creation_storcon and make it work (#11261)

Adds a basic test that makes the storcon issue explicit creation of a
timeline on safeekepers (main storcon PR in #11058). It was adapted from
`test_explicit_timeline_creation` from #11002.

Also, do a bunch of fixes needed to get the test work (the API
definitions weren't correct), and log more stuff when we can't create a
new timeline due to no safekeepers being active.

Part of #9011

---------

Co-authored-by: Arseny Sher <sher-ars@yandex.ru>

test_runner/fixtures/neon_fixtures.py

@@ -1321,6 +1321,28 @@ class NeonEnv:
         for f in futs:
             f.result()
 
+        # Last step: register safekeepers at the storage controller
+        if (
+            self.storage_controller_config is not None
+            and self.storage_controller_config.get("timelines_onto_safekeepers") is True
+        ):
+            for sk_id, sk in enumerate(self.safekeepers):
+                body = {
+                    "id": sk_id,
+                    "created_at": "2023-10-25T09:11:25Z",
+                    "updated_at": "2024-08-28T11:32:43Z",
+                    "region_id": "aws-us-east-2",
+                    "host": "127.0.0.1",
+                    "port": sk.port.pg,
+                    "http_port": sk.port.http,
+                    "https_port": None,
+                    "version": 5957,
+                    "availability_zone_id": f"us-east-2b-{sk_id}",
+                }
+
+                self.storage_controller.on_safekeeper_deploy(sk_id, body)
+                self.storage_controller.safekeeper_scheduling_policy(sk_id, "Active")
+
     def stop(self, immediate=False, ps_assert_metric_no_errors=False, fail_on_endpoint_errors=True):
         """
         After this method returns, there should be no child processes running.

test_runner/regress/test_wal_acceptor.py

@@ -2039,6 +2039,29 @@ def test_explicit_timeline_creation(neon_env_builder: NeonEnvBuilder):
     ep.safe_psql("CREATE TABLE IF NOT EXISTS t(key int, value text)")
 
 
+def test_explicit_timeline_creation_storcon(neon_env_builder: NeonEnvBuilder):
+    """
+    Test that having neon.safekeepers starting with g#n: with non zero n enables
+    generations, which as a side effect disables automatic timeline creation.
+    Like test_explicit_timeline_creation, but asks the storcon to
+    create membership conf & timeline.
+    """
+    neon_env_builder.num_safekeepers = 3
+    neon_env_builder.storage_controller_config = {
+        "timelines_onto_safekeepers": True,
+    }
+    env = neon_env_builder.init_start()
+
+    config_lines = [
+        "neon.safekeeper_proto_version = 3",
+    ]
+    ep = env.endpoints.create("main", config_lines=config_lines)
+
+    # endpoint should start.
+    ep.start(safekeeper_generation=1, safekeepers=[1, 2, 3])
+    ep.safe_psql("CREATE TABLE IF NOT EXISTS t(key int, value text)")
+
+
 # In this test we check for excessive START_REPLICATION and START_WAL_PUSH queries
 # when compute is active, but there are no writes to the timeline. In that case
 # pageserver should maintain a single connection to safekeeper and don't attempt