remove api that was scheduled for removal

patches/api/0006-Adventure.patch

@@ -374,10 +374,10 @@ index 0000000000000000000000000000000000000000..01cf89d3558132912c4d0eb48c98cd8c
 +}
 diff --git a/src/main/java/io/papermc/paper/event/player/AsyncChatDecorateEvent.java b/src/main/java/io/papermc/paper/event/player/AsyncChatDecorateEvent.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..d4c01e4d332b46f0b129dd5f9e9737ba19923562
+index 0000000000000000000000000000000000000000..2e492f4cd179135bd40ad951ab23acb562be2f06
 --- /dev/null
 +++ b/src/main/java/io/papermc/paper/event/player/AsyncChatDecorateEvent.java
-@@ -0,0 +1,118 @@
+@@ -0,0 +1,105 @@
 +package io.papermc.paper.event.player;
 +
 +import net.kyori.adventure.text.Component;
@@ -459,19 +459,6 @@ index 0000000000000000000000000000000000000000..d4c01e4d332b46f0b129dd5f9e9737ba
 +        this.result = result;
 +    }
 +
-+    /**
-+     * If this decorating is part of a preview request/response.
-+     *
-+     * @return {@code true} if part of previewing
-+     * @deprecated chat preview was removed in 1.19.3
-+     */
-+    @Deprecated(forRemoval = true, since = "1.19.3")
-+    @ApiStatus.ScheduledForRemoval(inVersion = "1.21")
-+    @Contract(value = "-> false", pure = true)
-+    public boolean isPreview() {
-+        return false;
-+    }
-+
 +    @Override
 +    public boolean isCancelled() {
 +        return this.cancelled;