FilesystemDeleteHandler: Fix misused week year flagged by error prone

The recent error prone version 2.3.3, that is included in most recent
Bazel@HEAD reports MisusedWeekYear pattern:

  Building plugins/delete-project/libdelete-project__plugin-class.jar
  FilesystemDeleteHandler.java:45: error: [MisusedWeekYear] \
  Use of "YYYY" (week year) in a date pattern without "ww"
  (week in year). You probably meant to use "yyyy" (year) instead.
  DateTimeFormatter.ofPattern("YYYYMMddHHmmss")
                               ^
  (see https://errorprone.info/bugpattern/MisusedWeekYear)

Bug: Issue 11658
Change-Id: I17bbd72a57137e897a992280ee954aeba4d4c28c
diff --git a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/DeleteTrashFolders.java b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/DeleteTrashFolders.java
index bd63e1f..ee44352 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/DeleteTrashFolders.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/DeleteTrashFolders.java
@@ -58,7 +58,7 @@
 
     /**
      * Newer trash folder name format. Besides the changes in TRASH_2, it uses a timestamp format
-     * (YYYYMMddHHmmss) instead of the epoch one for increased readability.
+     * (yyyyMMddHHmmss) instead of the epoch one for increased readability.
      */
     private static final Pattern TRASH_3 = Pattern.compile(".*\\.\\d{14}.%deleted%.git");
 
diff --git a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/FilesystemDeleteHandler.java b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/FilesystemDeleteHandler.java
index 003f154..c73f450 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/FilesystemDeleteHandler.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/deleteproject/fs/FilesystemDeleteHandler.java
@@ -43,7 +43,7 @@
 public class FilesystemDeleteHandler {
   private static final Logger log = LoggerFactory.getLogger(FilesystemDeleteHandler.class);
   private static final DateTimeFormatter FORMAT =
-      DateTimeFormatter.ofPattern("YYYYMMddHHmmss").withZone(ZoneId.of("UTC"));
+      DateTimeFormatter.ofPattern("yyyyMMddHHmmss").withZone(ZoneId.of("UTC"));
 
   private final GitRepositoryManager repoManager;
   private final DynamicSet<ProjectDeletedListener> deletedListeners;