fix: prevent duplicate alias in --empty mode for inline ref/source

DatabricksRelation inherited require_alias=True from BaseRelation, causing
render_limited() to inject a _dbt_limit_subq_* alias that conflicts with
user-provided AS aliases when running dbt run --empty.

Resolves dbt-labs/dbt-adapters#660 for Databricks, matching the fix already
applied to Snowflake (dbt-snowflake#980) and BigQuery (dbt-bigquery#1190).

Author: sd-db

dbt/adapters/databricks/relation.py

@@ -72,6 +72,7 @@ class DatabricksRelation(BaseRelation):
     quote_policy: Policy = field(default_factory=lambda: DatabricksQuotePolicy())
     include_policy: Policy = field(default_factory=lambda: DatabricksIncludePolicy())
     quote_character: str = "`"
+    require_alias: bool = False
     is_delta: Optional[bool] = None
     create_constraints: list[TypedConstraint] = field(default_factory=list)
     alter_constraints: list[TypedConstraint] = field(default_factory=list)

tests/functional/adapter/empty/__init__.py

@@ -0,0 +1,9 @@
+from dbt.tests.adapter.empty.test_empty import BaseTestEmpty, BaseTestEmptyInlineSourceRef
+
+
+class TestDatabricksEmpty(BaseTestEmpty):
+    pass
+
+
+class TestDatabricksEmptyInlineSourceRef(BaseTestEmptyInlineSourceRef):
+    pass

tests/functional/adapter/empty/test_empty.py

@@ -368,3 +368,16 @@ def test_render_constraints_for_create__with_constraints(
         relation.add_constraint(custom_constraint)
         relation.add_constraint(pk_constraint)
         assert relation.render_constraints_for_create() == "a > 1, PRIMARY KEY (a)"
+
+
+class TestDatabricksRenderLimited:
+    def test_render_limited_with_empty_no_alias(self):
+        relation = DatabricksRelation.create(
+            database="test_catalog",
+            schema="test_schema",
+            identifier="test_model",
+            limit=0,
+        )
+        result = relation.render_limited()
+        expected = "(select * from `test_catalog`.`test_schema`.`test_model` where false limit 0)"
+        assert result == expected