Grant pg_monitor to neon_superuser (#6691)

## Problem
The people want pg_monitor
https://github.com/neondatabase/neon/issues/6682
## Summary of changes
Gives the people pg_monitor

compute_tools/src/spec.rs

@@ -776,6 +776,7 @@ BEGIN
     END IF;
 END
 $$;"#,
+        "GRANT pg_monitor TO neon_superuser WITH ADMIN OPTION",
     ];
 
     let mut query = "CREATE SCHEMA IF NOT EXISTS neon_migration";

test_runner/regress/test_migrations.py

@@ -15,7 +15,7 @@ def test_migrations(neon_simple_env: NeonEnv):
 
     endpoint.wait_for_migrations()
 
-    num_migrations = 3
+    num_migrations = 4
 
     with endpoint.cursor() as cur:
         cur.execute("SELECT id FROM neon_migration.migration_id")
@@ -24,7 +24,7 @@ def test_migrations(neon_simple_env: NeonEnv):
 
     with open(log_path, "r") as log_file:
         logs = log_file.read()
-        assert "INFO handle_migrations: Ran 3 migrations" in logs
+        assert f"INFO handle_migrations: Ran {num_migrations} migrations" in logs
 
     endpoint.stop()
     endpoint.start()

test_runner/regress/test_neon_superuser.py

@@ -76,3 +76,21 @@ def test_neon_superuser(neon_simple_env: NeonEnv, pg_version: PgVersion):
             assert [r[0] for r in res] == [10, 20, 30, 40]
 
         wait_until(10, 0.5, check_that_changes_propagated)
+
+        # Test that pg_monitor is working for neon_superuser role
+        cur.execute("SELECT query from pg_stat_activity LIMIT 1")
+        assert cur.fetchall()[0][0] != "<insufficient privilege>"
+        # Test that pg_monitor is not working for non neon_superuser role without grant
+        cur.execute("CREATE ROLE not_a_superuser LOGIN PASSWORD 'Password42!'")
+        cur.execute("GRANT not_a_superuser TO neon_superuser WITH ADMIN OPTION")
+        cur.execute("SET ROLE not_a_superuser")
+        cur.execute("SELECT query from pg_stat_activity LIMIT 1")
+        assert cur.fetchall()[0][0] == "<insufficient privilege>"
+        cur.execute("RESET ROLE")
+        # Test that pg_monitor is working for non neon_superuser role with grant
+        cur.execute("GRANT pg_monitor TO not_a_superuser")
+        cur.execute("SET ROLE not_a_superuser")
+        cur.execute("SELECT query from pg_stat_activity LIMIT 1")
+        assert cur.fetchall()[0][0] != "<insufficient privilege>"
+        cur.execute("RESET ROLE")
+        cur.execute("DROP ROLE not_a_superuser")