Restore dedicated thread pool for include scanning in async execution.

Include scanning (`IncludeParser`) is predominantly a CPU-bound workload (regex and token parsing over C++ headers) rather than I/O-bound. Virtual threads do not unmount from carrier threads during CPU-intensive processing, which can monopolize the JVM carrier thread pool (`ForkJoinPool`) and starve other async tasks under high concurrency.

This change restores the dedicated bounded platform thread pool (`options.getIncludeScanningParallelism()`) for include scanning in async execution to properly bound CPU concurrency.

PiperOrigin-RevId: 971878996
Change-Id: I053f071eee970f4c06136b8b8850098edc87e87c

src/main/java/com/google/devtools/build/lib/includescanning/IncludeScanningModule.java

diff --git a/src/main/java/com/google/devtools/build/lib/includescanning/IncludeScanningModule.java b/src/main/java/com/google/devtools/build/lib/includescanning/IncludeScanningModule.java
index 6b1c8f9..9a2d247 100644
--- a/src/main/java/com/google/devtools/build/lib/includescanning/IncludeScanningModule.java
+++ b/src/main/java/com/google/devtools/build/lib/includescanning/IncludeScanningModule.java
@@ -67,7 +67,6 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -323,13 +322,8 @@
 
     @Override
     public void executorCreated() {
-      var useAsyncExecution = useAsyncExecution(env);
       int threads = options.getIncludeScanningParallelism();
-      if (useAsyncExecution) {
-        includePool =
-            Executors.newThreadPerTaskExecutor(
-                Thread.ofVirtual().name("Include scanner ", 0).factory());
-      } else if (threads > 0) {
+      if (threads > 0) {
         logger.atInfo().log("Include scanning configured to use a pool with %d threads", threads);
         if (options.getExperimentalReuseIncludeScanningThreads()) {
           includePool =