net-analyzer/netperf: use the MIT licensed version

As the net-analyzer/netperf stable version does not have a clear
License, the upstream Gentoo package has a masked ebuild that uses the
source from Github commit:
HewlettPackard/netperf@3bc455b

This change unmasks netperf-2.7.0_p20210121 for amd64 and arm64.

Also, added netperf to the github actions sync list.

Fixes: flatcar/Flatcar#1459

Signed-off-by: Adrian Vladu <avladu@cloudbasesolutions.com>

sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords

@@ -65,6 +65,9 @@
 =dev-python/lxml-5.2.1 ~arm64
 =dev-util/pahole-1.26 ~arm64
 
+# Needed for the MIT License
+=net-analyzer/netperf-2.7.0_p20210121 ~amd64 ~arm64
+
 # Needed for addressing CVE-2024-25629
 =net-dns/c-ares-1.27.0 ~amd64 ~arm64