jobs/ttcn3: io_uring: set memlock to unlimited

io_uring in the kernel memlocks a big amount of space with older
kernels, such as the kernel on host2-deb11build-ansible. It seemed to be
enough to increase it to 1 GiB. However now we see it failing again
with:

  failure during io_uring_queue_init(): Cannot allocate memory
  Aborted (core dumped)

Set it to unlimited to ensure that a low limit is not the reason we see
it failing. If it still happens after this, we probably need to make
sure that we don't run too many SUTs with io_uring in parallel on
jenkins nodes with older kernels.

Related: OS#6405
Change-Id: I39aaa2ed7d0310a12d0c4493a79ff46b2e7e2864
diff --git a/jobs/ttcn3-testsuites.yml b/jobs/ttcn3-testsuites.yml
index 2e01645..2c3e07d 100644
--- a/jobs/ttcn3-testsuites.yml
+++ b/jobs/ttcn3-testsuites.yml
@@ -301,8 +301,8 @@
                   ;;
               *-io_uring)
                   DIR="$(echo "{job-name}" | sed s/\-io_uring$//)"
-                  # OS#6405: set memlock to 1 GB for older kernels
-                  export DOCKER_ARGS="-e LIBOSMO_IO_BACKEND=IO_URING --ulimit memlock=1000000"
+                  # OS#6405: set memlock to unlimited for older kernels
+                  export DOCKER_ARGS="-e LIBOSMO_IO_BACKEND=IO_URING --ulimit memlock=-1"
                   ;;
               *-latest)
                   DIR="$(echo "{job-name}" | sed s/\-latest$//)"