Update runfiles usage example to use merge_all()
Update runfiles usage example to use merge_all()

In the example, we are merging a potentially very large list of runfiles - so we
should be using merge_all() to avoid exceeding depset depth limits, instead of
calling merge() in a loop.

RELNOTES: None.
PiperOrigin-RevId: 364640619

perezd/bazel,perezd/bazel,meteorcloudy/bazel,cushon/bazel,katre/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,bazelbuild/bazel,katre/bazel,perezd/bazel,bazelbuild/bazel,katre/bazel,cushon/bazel,meteorcloudy/bazel,perezd/bazel,meteorcloudy/bazel,cushon/bazel,twitter-forks/bazel,perezd/bazel,bazelbuild/bazel,perezd/bazel,bazelbuild/bazel,katre/bazel,meteorcloudy/bazel,cushon/bazel,twitter-forks/bazel,meteorcloudy/bazel,twitter-forks/bazel,katre/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,cushon/bazel,perezd/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,twitter-forks/bazel,cushon/bazel,katre/bazel,twitter-forks/bazel,twitter-forks/bazel,ButterflyNetwork/bazel