revert: drop foreign_key_action_clause abstraction

ON UPDATE CASCADE ON DELETE RESTRICT is standard SQL supported by
both MySQL and PostgreSQL. No need to abstract it — premature
generalization for backends we don't support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dimitri-yatsenko

src/datajoint/adapters/base.py

@@ -259,17 +259,6 @@ def make_full_table_name(self, database: str, table_name: str) -> str:
         """
         return f"{self.quote_identifier(database)}.{self.quote_identifier(table_name)}"
 
-    @property
-    def foreign_key_action_clause(self) -> str:
-        """
-        Referential action clause appended to FOREIGN KEY declarations.
-
-        Default: ``ON UPDATE CASCADE ON DELETE RESTRICT`` (MySQL/PostgreSQL).
-        Backends that don't support referential actions can override to
-        return ``""``.
-        """
-        return " ON UPDATE CASCADE ON DELETE RESTRICT"
-
     # =========================================================================
     # Type Mapping
     # =========================================================================

src/datajoint/declare.py

@@ -299,7 +299,7 @@ def compile_foreign_key(
     ref_table_name = adapter.make_full_table_name(parts[0], parts[1])
 
     foreign_key_sql.append(
-        f"FOREIGN KEY ({fk_cols}) REFERENCES {ref_table_name} ({pk_cols}){adapter.foreign_key_action_clause}"
+        f"FOREIGN KEY ({fk_cols}) REFERENCES {ref_table_name} ({pk_cols}) ON UPDATE CASCADE ON DELETE RESTRICT"
     )
 
     # declare unique index