set node name for k8s driver when appending nodes #1332

Job	Run time
build-ref (master)	2m 2s
build-ref (refs/tags/v0.5.1)	1m 16s
build-ref (refs/pull/731/head)	1m 33s
build-ref (cb185f095fd3d9444e0aa605d3789e9e05f2a1e7)	1m 17s
append	12s
cleanup (true)	5s
cleanup (false)	11s
config	18s
config-inline	7s
debug	13s
docker-context	9s
docker-driver	9s
driver (image=moby/buildkit:latest)	14s
driver (image=moby/buildkit:master network=host )	8s
endpoint	49s
error	27s
install	17s
k3s (v0.11.0-rc1)	59s
k3s (v0.10.5)	56s
multi	12s
main (latest)	13s
main (v0.4.1)	15s
main	7s
platforms	13s
standalone-action	15s
standalone-cmd	11s
standalone-install-error	13s
use (true)	7s
use (false)	7s
with-qemu (latest, all)	9s
with-qemu (latest, arm64,riscv64,arm)	9s
with-qemu (v0.4.1, all)	9s
with-qemu (v0.4.1, arm64,riscv64,arm)	9s
with-qemu (all)	20s
with-qemu (arm64,riscv64,arm)	11s
	14m 22s

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