RPC binder: one more pool test flake fix

Fixes: 285094756
Test: binderRpcTest
Change-Id: Ie36371803c03ab4e25f7bee0a26842c5f2dc92e4
diff --git a/libs/binder/tests/binderRpcTest.cpp b/libs/binder/tests/binderRpcTest.cpp
index 505f30f..f88cfd6 100644
--- a/libs/binder/tests/binderRpcTest.cpp
+++ b/libs/binder/tests/binderRpcTest.cpp
@@ -461,8 +461,11 @@
 
     EXPECT_GE(epochMsAfter, epochMsBefore + 2 * sleepMs);
 
-    // Potential flake, but make sure calls are handled in parallel.
-    EXPECT_LE(epochMsAfter, epochMsBefore + 4 * sleepMs);
+    // Potential flake, but make sure calls are handled in parallel. Due
+    // to past flakes, this only checks that the amount of time taken has
+    // some parallelism. Other tests such as ThreadPoolGreaterThanEqualRequested
+    // check this more exactly.
+    EXPECT_LE(epochMsAfter, epochMsBefore + (numCalls - 1) * sleepMs);
 }
 
 TEST_P(BinderRpc, ThreadPoolOverSaturated) {