Fix AttachmentReconciler repeated execution (#4052)

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#### What type of PR is this?
/kind bug
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#### What this PR does / why we need it:
Fix AttachmentReconciler repeated execution.

#### Which issue(s) this PR fixes:

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Fixes #3746

#### Special notes for your reviewer:
The reconile method in run.halo.app.core.extension.reconciler.attachment.AttachmentReconciler will be executed repeatedly, uploading an attachment will be executed twice, because updating the finalizers property will be in onUpdate of run.halo.app.extension.controller.ExtensionWatcher Will request duplicate addition, I provide a fix for you to review
#### Does this PR introduce a user-facing change?

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```release-note
修复 AttachmentReconciler 重复执行
```

application/src/main/java/run/halo/app/core/extension/reconciler/attachment/AttachmentReconciler.java

@@ -40,11 +40,7 @@ public class AttachmentReconciler implements Reconciler<Request> {
         client.fetch(Attachment.class, request.name()).ifPresent(attachment -> {
             // TODO Handle the finalizer
             if (attachment.getMetadata().getDeletionTimestamp() != null) {
-                attachmentService.delete(attachment)
-                    .doOnNext(deletedAttachment -> {
-                        removeFinalizer(attachment.getMetadata().getName());
-                    })
-                    .blockOptional();
+                removeFinalizer(attachment);
                 return;
             }
             // add finalizer
@@ -89,14 +85,25 @@ public class AttachmentReconciler implements Reconciler<Request> {
             });
     }
 
-    void removeFinalizer(String attachmentName) {
-        client.fetch(Attachment.class, attachmentName).ifPresent(attachment -> {
-            var finalizers = attachment.getMetadata().getFinalizers();
-            if (finalizers != null && finalizers.remove(Constant.FINALIZER_NAME)) {
-                // update it
-                client.update(attachment);
-            }
-        });
+    void removeFinalizer(Attachment oldAttachment) {
+        if (!hasFinalizer(oldAttachment, Constant.FINALIZER_NAME)) {
+            return;
+        }
+        attachmentService.delete(oldAttachment).block();
+        client.fetch(Attachment.class, oldAttachment.getMetadata().getName())
+            .ifPresent(attachment -> {
+                var finalizers = attachment.getMetadata().getFinalizers();
+                if (hasFinalizer(attachment, Constant.FINALIZER_NAME)
+                    && finalizers.remove(Constant.FINALIZER_NAME)) {
+                    // update it
+                    client.update(attachment);
+                }
+            });
+    }
+
+    boolean hasFinalizer(Attachment attachment, String finalizer) {
+        var finalizers = attachment.getMetadata().getFinalizers();
+        return finalizers != null && finalizers.contains(finalizer);
     }
 
     void addFinalizerIfNotSet(String attachmentName, Set<String> existingFinalizers) {