selftests/bpf: Remove test_xdp_redirect_multi.sh

The tests done by test_xdp_redirect_multi.sh are now fully covered by
the CI through test_xdp_veth.c.

Remove test_xdp_redirect_multi.sh
Remove xdp_redirect_multi.c that was used by the script to load and
attach the BPF programs.
Remove their entries in the Makefile

Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@bootlin.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250212-redirect-multi-v5-6-fd0d39fca6e6@bootlin.com

Author: bastien-curutchet

tools/testing/selftests/bpf/Makefile

@@ -100,7 +100,6 @@ TEST_FILES = xsk_prereqs.sh $(wildcard progs/btf_dump_test_case_*.c)
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
-	test_xdp_redirect_multi.sh \
 	test_tunnel.sh \
 	test_lwt_seg6local.sh \
 	test_lirc_mode2.sh \
@@ -135,7 +134,6 @@ TEST_GEN_PROGS_EXTENDED = \
 	veristat \
 	xdp_features \
 	xdp_hw_metadata \
-	xdp_redirect_multi \
 	xdp_synproxy \
 	xdping \
 	xskxceiver