Bump up velox_exec_test timeout limit (#6571)

Summary:
velox_exec_test is failing with timeout, reason being sum of different
test suites, example of test suites that took more than 3 minutes:
TableScanTest 3minutes,
SpillTestSuite/SpillTest 4 minutes
HashJoinTest 7 minutes
TableWriterTest 4 minutes

Bump up the test timeout limit.

Pull Request resolved: #6571

Reviewed By: Yuhta

Differential Revision: D49282786

Pulled By: kewang1024

fbshipit-source-id: 079493db8ee15898a8d849873491e6482a984352

velox/exec/tests/CMakeLists.txt

@@ -99,6 +99,8 @@ add_test(
   COMMAND velox_exec_test
   WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
 
+set_tests_properties(velox_exec_test PROPERTIES TIMEOUT 3000)
+
 add_test(
   NAME velox_exec_infra_test
   COMMAND velox_exec_infra_test