test: user_defined_function_test: raise Lua timeout
test: user_defined_function_test: raise Lua timeout

user_defined_function_test fails sporadically in debug mode
due to lua timeout. Raise the timeout to avoid the failure, but
not so much that the test that expects timout becomes too slow.

Fixes #8746.

Closes #8747

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla