MM-62751: [Shared Channels] Allow remote users to be discoverable in the create DM/GM modal (#30918)

server/channels/db/migrations/mysql/000139_remoteclusters_add_last_global_user_sync_at.down.sql

@@ -0,0 +1,14 @@
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE TABLE_SCHEMA = DATABASE()
+        AND TABLE_NAME = 'RemoteClusters'
+        AND COLUMN_NAME = 'LastGlobalUserSyncAt'
+    ) > 0,
+    'ALTER TABLE RemoteClusters DROP COLUMN LastGlobalUserSyncAt',
+    'SELECT 1'
+));
+
+PREPARE alterIfExists FROM @preparedStatement;
+EXECUTE alterIfExists;
+DEALLOCATE PREPARE alterIfExists;

server/channels/db/migrations/mysql/000139_remoteclusters_add_last_global_user_sync_at.up.sql

@@ -0,0 +1,14 @@
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE TABLE_SCHEMA = DATABASE()
+        AND TABLE_NAME = 'RemoteClusters'
+        AND COLUMN_NAME = 'LastGlobalUserSyncAt'
+    ) > 0,
+    'SELECT 1',
+    'ALTER TABLE RemoteClusters ADD COLUMN LastGlobalUserSyncAt bigint DEFAULT 0'
+));
+
+PREPARE alterIfNotExists FROM @preparedStatement;
+EXECUTE alterIfNotExists;
+DEALLOCATE PREPARE alterIfNotExists;