Increase thread pool for VHAL 2.1

Fixes: 36510399

Test: runtest -x
packages/services/Car/tests/vehiclehal_test/src/com/android/car/vehiclehal/test/E2ePerformanceTest.java

Change-Id: Id5638f63c6ff23bb78675fa07a2f3922bb7e3d73
diff --git a/automotive/vehicle/2.1/default/service.cpp b/automotive/vehicle/2.1/default/service.cpp
index bae64fd..03a0a5d 100644
--- a/automotive/vehicle/2.1/default/service.cpp
+++ b/automotive/vehicle/2.1/default/service.cpp
@@ -88,7 +88,7 @@
 
     Vehicle_V2_1 vehicle21(vehicleManager.get());
 
-    configureRpcThreadpool(1, true /* callerWillJoin */);
+    configureRpcThreadpool(4, true /* callerWillJoin */);
 
     ALOGI("Registering as service...");
     status_t status = vehicle21.registerAsService();