selftests/bpf: migrate bpf flow dissectors tests to test_progs

JIRA: https://issues.redhat.com/browse/RHEL-78201

commit 20203a5
Author: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Date:   Wed Nov 20 08:43:23 2024 +0100

    selftests/bpf: migrate bpf flow dissectors tests to test_progs

    test_flow_dissector.sh loads flow_dissector program and subprograms,
    creates and configured relevant tunnels and interfaces, and ensure that
    the bpf dissection is actually performed correctly. Similar tests exist
    in test_progs (thanks to flow_dissector.c) and run the same programs,
    but those are only executed with BPF_PROG_RUN: those tests are then
    missing some coverage (eg: coverage for flow keys manipulated when the
    configured flower uses a port range, which has a dedicated test in
    test_flow_dissector.sh)

    Convert test_flow_dissector.sh into test_progs so that the corresponding
    tests are also run in CI.

    Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
    Acked-by: Stanislav Fomichev <sdf@fomichev.me>
    Link: https://lore.kernel.org/r/20241120-flow_dissector-v3-13-45b46494f937@bootlin.com
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

Author: jeromemarchand