build(CI): Increase timeout for velox_exec_test temporarily (facebookincubator#13982)

Summary:
While the actual issue is being addressed in facebookincubator#13879 which ran into unexpected issues.

Pull Request resolved: facebookincubator#13982

Reviewed By: mbasmanova

Differential Revision: D77668482

Pulled By: kagamiori

fbshipit-source-id: 4537fb2c138381ab6c73223f2669ed6ae2eb797a

Author: czentgr

velox/exec/tests/CMakeLists.txt

@@ -120,7 +120,9 @@ add_test(
   COMMAND velox_exec_test
   WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
 
-set_tests_properties(velox_exec_test PROPERTIES TIMEOUT 3000)
+# TODO: Revert back to 3000 once is fixed.
+# https://github.com/facebookincubator/velox/issues/13879
+set_tests_properties(velox_exec_test PROPERTIES TIMEOUT 6000)
 
 add_test(
   NAME velox_exec_infra_test