tests: Fix transient failure in ping6 header modify. #2517

Job	Run time
osx clang --disable-ssl	1m 49s
dpdk gcc (ubuntu-24.04)	5s
build oss-fuzz fuzzers	3m 0s
linux rpm fedora	4m 13s
libreswan (ubuntu-24.04)	2m 24s
linux deb no dpdk	5m 11s
clang-analyze	20m 27s
linux gcc --disable-ssl	3m 22s
linux clang --disable-ssl	2m 46s
linux gcc c99	2m 43s
linux clang c99	3m 4s
linux gcc test	8m 26s
linux clang address,undefined test	16m 22s
linux gcc test --enable-shared	11m 8s
linux clang test --enable-shared	10m 58s
linux gcc check check-dpdk dpdk	17m 11s
linux clang check check-dpdk dpdk	17m 34s
linux gcc test -ljemalloc	9m 39s
linux clang test -ljemalloc	8m 43s
linux gcc --enable-afxdp	2m 44s
linux clang --enable-afxdp	2m 37s
linux gcc dpdk --enable-shared	3m 51s
linux clang dpdk --enable-shared	3m 49s
linux gcc dpdk-shared	3m 33s
linux clang dpdk-shared	3m 15s
linux gcc dpdk-shared --enable-shared	4m 5s
linux clang dpdk-shared --enable-shared	3m 40s
linux gcc m32 --disable-ssl	2m 53s
linux gcc check-ovsdb-cluster	6m 47s
linux gcc check-kernel -100	10m 33s
linux gcc check-kernel 100-	15m 36s
linux clang address,undefined check-kernel -100	12m 44s
linux clang address,undefined check-kernel 100-	17m 20s
linux gcc check-offloads -100	9m 25s
linux gcc check-offloads 100-	11m 25s
linux gcc dpdk check-system-userspace	10m 54s
linux clang address,undefined dpdk check-system-userspace	14m 33s
linux gcc dpdk check-system-tso	10m 51s
linux gcc dpdk check-afxdp	10m 52s
	5h 10m 32s

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