Fix #11528: Don't call config_flush_cache() in bug_actiongroup_ext.php

There is no need to call config_flush_cache() in bug_actiongroup_ext.php
because the configuration cache already takes into account whether a
configuration setting is per-user and per-project.

Additionally, bug_actiongroup_ext.php has been cleaned up to reduce code
complexity and increase the efficiency of this page.

bug_actiongroup_ext.php

@@ -76,48 +76,26 @@
 
 $t_failed_ids = array();
 
-# validate all bugs before we start the processing, we may fail the whole action
-# group, or some of the bugs.
-foreach( $t_projects_bugs as $t_project_id => $t_bug_ids ) {
-	if ( $t_bug->project_id != helper_get_current_project() ) {
-		# in case the current project is not the same project of the bug we are viewing...
-		# ... override the current project. This to avoid problems with categories and handlers lists etc.
-		$g_project_override = $t_bug->project_id;
-		/** @todo (thraxisp) the next line goes away if the cache was smarter and used project */
-		config_flush_cache(); # flush the config cache so that configs are refetched
-	}
-
-	foreach( $t_bug_ids as $t_bug_id ) {
+foreach( $t_projects_bugs as $t_project_id => $t_bugs ) {
+	$g_project_override = $t_project_id;
+	foreach( $t_bugs as $t_bug_id ) {
 		$t_result = bug_group_action_validate( $f_action, $t_bug_id );
-		if ( $t_result !== true ) {
+		if( $t_result !== true ) {
 			foreach( $t_result as $t_key => $t_value ) {
 				$t_failed_ids[$t_key] = $t_value;
 			}
 		}
-	}
-}
-
-// process bugs that are not already failed by validation.
-foreach( $t_projects_bugs as $t_project_id => $t_bug_ids ) {
-	if ( $t_bug->project_id != helper_get_current_project() ) {
-		// in case the current project is not the same project of the bug we are viewing...
-		// ... override the current project. This to avoid problems with categories and handlers lists etc.
-		$g_project_override = $t_bug->project_id;
-		/** @todo (thraxisp) the next line goes away if the cache was smarter and used project */
-		config_flush_cache(); // flush the config cache so that configs are refetched
-	}
-
-	foreach( $t_bug_ids as $t_bug_id ) {
-		# do not process this bug if validation failed for it.
-		if ( !isset( $t_failed_ids[$t_bug_id] ) ) {
+		if( !isset( $t_failed_ids[$t_bug_id] ) ) {
 			$t_result = bug_group_action_process( $f_action, $t_bug_id );
-			if ( $t_result !== true ) {
+			if( $t_result !== true ) {
 				$t_failed_ids[] = $t_result;
 			}
 		}
 	}
 }
 
+$g_project_override = null;
+
 form_security_purge( $t_form_name );
 
 if ( count( $t_failed_ids ) > 0 ) {