command: Add additional string map unit test case
command: Add additional string map unit test case

This test already passes, but it's a good corner case to test to avoid
running into regressions.

Signed-off-by: Sebastian Wicki <db043b2055cb3a47b2eb0b5aebf4e114a8c24a5a@isovalent.com>

michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium