tests: net: icmpv4 move to new ztest API

Move net icmpv4 tests to use new ztest API
1. Add teardown, remove addr
2. Fix a packet release bug in test_send_echo_req_bad_opt
3. Combine send_echo_req/rep, as they should be run in sequence

Signed-off-by: Hu Zhenyu <zhenyu.hu@intel.com>