Fix Libbinder RemoveFromCacheOnServerDeath test

Get pid before killing the server

Test: atest binderCacheUnitTest
Bug: 333854840
Flag: Exempt Bugfix
Change-Id: I7d07c34e89867920f03545557eb51d4c307ec357
diff --git a/libs/binder/tests/binderCacheUnitTest.cpp b/libs/binder/tests/binderCacheUnitTest.cpp
index 92dab19..482d197 100644
--- a/libs/binder/tests/binderCacheUnitTest.cpp
+++ b/libs/binder/tests/binderCacheUnitTest.cpp
@@ -137,9 +137,9 @@
     ASSERT_EQ(binder1, result);
 
     // Kill the server, this should remove from cache.
-    foo.killServer(binder1);
     pid_t pid;
     ASSERT_EQ(OK, binder1->getDebugPid(&pid));
+    foo.killServer(binder1);
     system(("kill -9 " + std::to_string(pid)).c_str());
 
     sp<IBinder> binder2 = sp<BBinder>::make();