[Test] Skip IPv6LinkLocalWithDefaultRouteFlag on Kernel 4.4

The test failed on kernel 4.4 since the kernel does not provide an IPv6
link-local address when an interface is added to a network. The IPv6
link-local address is a prerequisite for this test. Considering 4.4 is
outdated and EOL'ed, skip the test directly.

Bug: 259798540
Test: atest ResolverMultinetworkTest (on walleye)
Change-Id: Id2951ff730cfb196d9e21e6313530a6ee728f89e