test-network: drop old kernel support and workaround for fixed kernel bug

test-network: drop old kernel support and workaround for fixed kernel bug

- l3mdev in fib rules is supported since
https://github.com/torvalds/linux/commit/96c63fa7393d0a346acfe5a91e0c7d4c7782641b (v4.8).
- uid range in fib rules is supported since
https://github.com/torvalds/linux/commit/622ec2c9d52405973c9f1ca5116eb1c393adfc7d (v4.10).
- port range and ip proto in fib rules is supported since
https://github.com/torvalds/linux/commit/bfff4862653bb96001ab57c1edd6d03f48e5f035 (v4.17).
- interface alternative name is supported since
https://github.com/torvalds/linux/commit/36fbf1e52bd3ff8a5cb604955eedfc9350c2e6cc (v5.5).
- SRIOV on netdevsim is supported since
https://github.com/torvalds/linux/commit/79579220566cd33fe3b15ce8249c57e10251b258 (4.16).
- nexthop is supported since
https://github.com/torvalds/linux/commit/65ee00a9409f751188a8cdc0988167858eb4a536 (v5.3).
- bridge MDB entries on bridge master is supported since
https://github.com/torvalds/linux/commit/1bc844ee0faa1b92e3ede00bdd948021c78d7088 (v5.4).