test: revert global current_time stub (conflicts with Patchwork)

Patchwork (used by Brain Monkey) requires it be loaded before any function it
may need to redefine. Defining current_time() in bootstrap triggers
DefinedTooEarly exceptions across the suite. Will mock via
Functions\when() in BaseTestCase::setUp instead.

Agent-Session: cowork-ci-parity-20260414

tests/bootstrap.php

@@ -61,22 +61,6 @@ if ( ! defined( 'OBJECT' ) ) {
     define( 'OBJECT', 'OBJECT' );
 }
 
-/**
- * current_time() stub — WordPress returns formatted timestamps.
- * Used by class-logger.php (which Publisher/ChiefEditor/etc call).
- * Using a real function (not Brain Monkey mock) so tests that don't explicitly
- * set up expectations for current_time still get a sensible value.
- */
-if ( ! function_exists( 'current_time' ) ) {
-    // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedFunctionFound
-    function current_time( $type = 'mysql', $gmt = 0 ) {
-        if ( $type === 'timestamp' || $type === 'U' ) {
-            return time();
-        }
-        return gmdate( 'Y-m-d H:i:s' );
-    }
-}
-
 /**
  * Minimal WP_Query stub for unit tests.
  *