[conn] Update tb name
[conn] Update tb name

With PR #8654 merged, Connectivity test does not have a default dut name
anymore. This PR adds a default tb name for connectivity test.

Signed-off-by: Cindy Chen <399ad771a111eac8923348b1e2af093034e5d4f1@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan