migrations: drop search_documents_package_path_fkey

The search_documents_package_path_fkey FK is dropped.

For golang/go#39629

Change-Id: I93da9209475c6a17fb5d137b99192d78d4a55b81
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/259009
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

migrations/000032_drop_search_documents_package_path_fkey.down.sql

@@ -0,0 +1,12 @@
+-- Copyright 2020 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+ALTER TABLE search_documents
+    ADD CONSTRAINT search_documents_package_path_fkey
+        FOREIGN KEY (package_path, module_path, version)
+        REFERENCES packages(path, module_path, version) ON DELETE CASCADE;
+
+END;

migrations/000032_drop_search_documents_package_path_fkey.up.sql

@@ -0,0 +1,9 @@
+-- Copyright 2020 The Go Authors. All rights reserved.
+-- Use of this source code is governed by a BSD-style
+-- license that can be found in the LICENSE file.
+
+BEGIN;
+
+ALTER TABLE search_documents DROP CONSTRAINT search_documents_package_path_fkey;
+
+END;