Update --skip-optimization doc block and verify import query result in Behat test

Author: swissspidy

features/db-import.feature

@@ -391,6 +391,12 @@ Feature: Import a WordPress database
       """
     And the side_effect.sql file should not exist
 
+    When I run `wp db query 'SELECT id FROM wp_cli_meta_test;' --skip-column-names`
+    Then STDOUT should be:
+      """
+      42
+      """
+
   @require-mysql-or-mariadb
   Scenario: `wp db import` does not execute embedded client meta-commands in dump content
     Given a WP install

src/DB_Command.php

@@ -926,7 +926,7 @@ private function command_supports_option( $command, $option ) {
 	 * : Extra arguments to pass to mysql. [Refer to mysql binary docs](https://dev.mysql.com/doc/refman/8.0/en/mysql-command-options.html).
 	 *
 	 * [--skip-optimization]
-	 * : When using an SQL file, do not include speed optimization such as disabling auto-commit and key checks.
+	 * : Do not disable unique checks and foreign key checks during import.
 	 *
 	 * [--skip-sql-mode-compat]
 	 * : Do not adapt the session SQL mode for WordPress compatibility. By default, `wp db import` strips the SQL modes that WordPress Core disables (such as `STRICT_TRANS_TABLES` and `NO_ZERO_DATE`) so that dumps containing legacy values like `0000-00-00` import cleanly. Pass this flag to import under the server's own SQL modes instead.