Some work on reducing test setup overhead

With the introduction of test-local tenants and timelines, we can still
allow tests to share a pageserver and/or safekeeper, removing the overhead
of setting up those components.

Future work can add wrappers for Pageserver, Safekeepers, and other APIs
that expose tenant-level configuration options that shouldn't impact
concurrent or sequential tests that reuse the same PS/SK resources.

Important note: This doesn't yet work consistently for all updated tests.

[skip ci]

test_runner/fixtures/function/neon_storage.py

@@ -0,0 +1,48 @@
+from typing import Iterator, Optional, Dict, Any
+
+import pytest
+from _pytest.fixtures import FixtureRequest
+
+from fixtures.neon_fixtures import NeonEnv
+from fixtures.shared_fixtures import TTenant, TTimeline
+
+@pytest.fixture(scope="function")
+def tenant_config() -> Dict[str, Any]:
+    return dict()
+
+@pytest.fixture(scope="function")
+def tenant(
+    neon_shared_env: NeonEnv,
+    request: FixtureRequest,
+    tenant_config: Optional[Dict[str, Any]] = None,
+) -> Iterator[TTenant]:
+    tenant = TTenant(env=neon_shared_env, name=request.node.name, config=tenant_config)
+    yield tenant
+    tenant.shutdown_resources()
+
+
+@pytest.fixture(scope="function")
+def timeline(
+    tenant: TTenant,
+) -> Iterator[TTimeline]:
+    timeline = tenant.default_timeline
+    yield timeline
+
+
+@pytest.fixture(scope="function")
+def exclusive_tenant(
+    neon_env: NeonEnv,
+    request: FixtureRequest,
+    tenant_config: Optional[Dict[str, Any]] = None,
+) -> Iterator[TTenant]:
+    tenant = TTenant(env=neon_env, name=request.node.name, config=tenant_config)
+    yield tenant
+    tenant.shutdown_resources()
+
+
+@pytest.fixture(scope="function")
+def exclusive_timeline(
+    exclusive_tenant: TTenant,
+) -> Iterator[TTimeline]:
+    timeline = exclusive_tenant.default_timeline
+    yield timeline