Gate printMountItem in error handlers behind enableFabricLogs (#56012)

Summary:
Two `printMountItem()` call sites in `MountItemDispatcher.kt` error handlers are not gated behind `ReactNativeFeatureFlags.enableFabricLogs()`, while every other `printMountItem` call site in the same file is.

When a Fabric mount operation fails under memory pressure, the unguarded error handler calls `toString()` on every mount item in the batch — each using `String.format()` — which triggers a fatal `OutOfMemoryError` (Android 256MB heap limit). The device is already low on memory when the original mount error occurs, so allocating diagnostic strings for the entire batch is the killing blow.

**Impact:** 67 affected users in production, 87% Android 16, all Samsung devices.

<details>
<summary>Production stacktrace (67 occurrences)</summary>

```
java.lang.OutOfMemoryError: Failed to allocate a 48 byte allocation with 2222800 free bytes and 2170KB until OOM, target footprint 268435456, growth limit 268435456; giving up on allocation because <1% of heap free after GC.
at java.util.Formatter.parse(Formatter.java:2737)
at java.util.Formatter.format(Formatter.java:2686)
at java.util.Formatter.format(Formatter.java:2640)
at java.lang.String.format(String.java:4489)
at com.facebook.react.fabric.mounting.mountitems.IntBufferBatchMountItem.toString(IntBufferBatchMountItem.kt:220)
at com.facebook.react.fabric.mounting.MountItemDispatcher$Companion.printMountItem(MountItemDispatcher.kt:358)
at com.facebook.react.fabric.mounting.MountItemDispatcher$Companion.access$printMountItem(MountItemDispatcher.kt:337)
at com.facebook.react.fabric.mounting.MountItemDispatcher.dispatchMountItems(MountItemDispatcher.kt:230)
at com.facebook.react.fabric.mounting.MountItemDispatcher.tryDispatchMountItems(MountItemDispatcher.kt:88)
at com.facebook.react.fabric.FabricUIManager$DispatchUIFrameCallback.doFrameGuarded(FabricUIManager.java:1484)
at com.facebook.react.uimanager.GuardedFrameCallback.doFrame(GuardedFrameCallback.kt:25)
at com.facebook.react.modules.core.ReactChoreographer.frameCallback$lambda$1(ReactChoreographer.kt:59)
```

Device: Samsung SM-S938B (Galaxy S25 Ultra), Android 16, 12GB RAM
Heap limit: 256MB, <1% free after GC
</details>

**Fix:**
Gate the two remaining `printMountItem` call sites behind `enableFabricLogs()`, matching the existing pattern used at all other call sites in the same file.

## Changelog:

[ANDROID] [FIXED] - Gate diagnostic `printMountItem` calls in `MountItemDispatcher` error handlers behind `enableFabricLogs()` to prevent OOM crash

Pull Request resolved: #56012

Test Plan:
Applied as a patch to a production app. OOM crash from the unguarded error handler path no longer occurs — confirmed over several weeks with 67 previously affected users.

The change is strictly additive gating — no logic changes. All other `printMountItem` call sites in the same file already use the same `enableFabricLogs()` guard, so this just makes the two error-handler sites consistent.

Reviewed By: javache, shwanton

Differential Revision: D97414011

Pulled By: alanleedev

fbshipit-source-id: 49818d58cacc7a164f71f33118a74e2b75dae6bc

Author: JakobFelixJulius

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/MountItemDispatcher.kt

@@ -120,7 +120,7 @@ internal class MountItemDispatcher(
             // items
             addViewCommandMountItem(mountItem)
           }
-        } else {
+        } else if (ReactNativeFeatureFlags.enableFabricLogs()) {
           printMountItem(item, "dispatchExternalMountItems: mounting failed with ${e.message}")
         }
       }
@@ -247,12 +247,14 @@ internal class MountItemDispatcher(
         } catch (e: Throwable) {
           // If there's an exception, we want to log diagnostics in prod and rethrow.
           FLog.e(TAG, "dispatchMountItems: caught exception, displaying mount state", e)
-          for (m in items) {
-            if (m === mountItem) {
-              // We want to mark the mount item that caused exception
-              FLog.e(TAG, "dispatchMountItems: mountItem: next mountItem triggered exception!")
+          if (ReactNativeFeatureFlags.enableFabricLogs()) {
+            for (m in items) {
+              if (m === mountItem) {
+                // We want to mark the mount item that caused exception
+                FLog.e(TAG, "dispatchMountItems: mountItem: next mountItem triggered exception!")
+              }
+              printMountItem(m, "dispatchMountItems: mountItem")
             }
-            printMountItem(m, "dispatchMountItems: mountItem")
           }
 
           if (mountItem.getSurfaceId() != View.NO_ID) {