Split up local cluster tests into separate CI steps (backport #22295) (#22303)

* Split up local cluster tests into separate CI steps (#22295)

* Split up local cluster tests into separate CI steps

* Update buildkite-pipeline.sh

(cherry picked from commit 0e1afcbb26)

# Conflicts:
#	local-cluster/tests/local_cluster.rs

* resolve conflicts

Co-authored-by: Justin Starry <justin@solana.com>

ci/run-local.sh

@@ -27,6 +27,8 @@ steps+=(test-stable-perf)
 steps+=(test-downstream-builds)
 steps+=(test-bench)
 steps+=(test-local-cluster)
+steps+=(test-local-cluster-flakey)
+steps+=(test-local-cluster-slow)
 
 step_index=0
 if [[ -n "$1" ]]; then