Drop dead databinding ignore and add benchmark to apiValidation (#6432)

- Remove `com/getstream/sdk/chat/databinding` from ignoredPackages —
  the `com.getstream.sdk` namespace no longer exists in the repo.
- Add `stream-chat-android-benchmark` to ignoredProjects so the list
  enumerates every non-validated module.

Author: andremion

build.gradle.kts

@@ -114,10 +114,10 @@ tasks.withType<Delete> {
 }
 
 apiValidation {
-    ignoredPackages.add("com/getstream/sdk/chat/databinding")
     ignoredPackages.add("io/getstream/chat/android/ui/databinding")
 
     ignoredProjects += listOf(
+        "stream-chat-android-benchmark",
         "stream-chat-android-client-test",
         "stream-chat-android-compose-sample",
         "stream-chat-android-docs",