Deprecate blaze_query.Rule.is_skylark.
Deprecate blaze_query.Rule.is_skylark.

It's never been populated by Bazel ever.

Fixes #11006

RELNOTES: None
PiperOrigin-RevId: 302673705

perezd/bazel,twitter-forks/bazel,katre/bazel,ButterflyNetwork/bazel,akira-baruah/bazel,akira-baruah/bazel,bazelbuild/bazel,twitter-forks/bazel,dslomov/bazel,werkt/bazel,safarmer/bazel,twitter-forks/bazel,katre/bazel,meteorcloudy/bazel,perezd/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,ulfjack/bazel,werkt/bazel,davidzchen/bazel,dslomov/bazel-windows,dslomov/bazel-windows,meteorcloudy/bazel,ulfjack/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,safarmer/bazel,katre/bazel,katre/bazel,perezd/bazel,safarmer/bazel,dslomov/bazel-windows,perezd/bazel,dslomov/bazel,meteorcloudy/bazel,bazelbuild/bazel,dslomov/bazel,safarmer/bazel,akira-baruah/bazel,davidzchen/bazel,perezd/bazel,dslomov/bazel,ButterflyNetwork/bazel,cushon/bazel,akira-baruah/bazel,davidzchen/bazel,davidzchen/bazel,perezd/bazel,werkt/bazel,meteorcloudy/bazel,ulfjack/bazel,akira-baruah/bazel,ulfjack/bazel,dslomov/bazel-windows,cushon/bazel,twitter-forks/bazel,akira-baruah/bazel,cushon/bazel,ulfjack/bazel,dslomov/bazel-windows,dslomov/bazel,twitter-forks/bazel,safarmer/bazel,bazelbuild/bazel,werkt/bazel,cushon/bazel,twitter-forks/bazel,katre/bazel,perezd/bazel,werkt/bazel,bazelbuild/bazel,ulfjack/bazel,cushon/bazel,davidzchen/bazel,werkt/bazel,davidzchen/bazel,bazelbuild/bazel,safarmer/bazel,cushon/bazel,meteorcloudy/bazel,meteorcloudy/bazel,meteorcloudy/bazel,katre/bazel,davidzchen/bazel,ulfjack/bazel,ButterflyNetwork/bazel,dslomov/bazel,dslomov/bazel,dslomov/bazel-windows