Replace go-migrate with morph (#19116)

db/migrations/postgres/000053_create_retention_policies.up.sql

@@ -0,0 +1,44 @@
+CREATE TABLE IF NOT EXISTS retentionpolicies (
+	id VARCHAR(26),
+	displayname VARCHAR(64),
+	postduration bigint,
+    PRIMARY KEY (id)
+);
+
+CREATE TABLE IF NOT EXISTS retentionpoliciesteams (
+	PolicyId varchar(26),
+    teamid varchar(26),
+    PRIMARY KEY (teamid)
+);
+
+CREATE TABLE IF NOT EXISTS retentionpolicieschannels (
+	policyid varchar(26),
+    channelid varchar(26),
+    PRIMARY KEY (channelid)
+);
+
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'fk_retentionpoliciesteams_retentionpolicies') THEN
+        ALTER TABLE retentionpoliciesteams
+            ADD CONSTRAINT fk_retentionpoliciesteams_retentionpolicies
+            FOREIGN KEY (policyid) REFERENCES retentionpolicies (id) ON DELETE CASCADE;
+    END IF;
+END;
+$$;
+
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'fk_retentionpolicieschannels_retentionpolicies') THEN
+        ALTER TABLE retentionpolicieschannels
+            ADD CONSTRAINT fk_retentionpolicieschannels_retentionpolicies
+            FOREIGN KEY (policyid) REFERENCES retentionpolicies (id) ON DELETE CASCADE;
+    END IF;
+END;
+$$;
+
+CREATE INDEX IF NOT EXISTS IDX_RetentionPoliciesTeams_PolicyId ON retentionpoliciesteams (policyid);
+CREATE INDEX IF NOT EXISTS IDX_RetentionPoliciesChannels_PolicyId ON retentionpolicieschannels (policyid);
+
+DROP INDEX IF EXISTS IDX_RetentionPolicies_DisplayName_Id;
+CREATE INDEX IF NOT EXISTS IDX_RetentionPolicies_DisplayName ON retentionpolicies (displayname);