Fixup scripts to set up a new CI node (#9348)

* Clean up node setup scripts for new CI boxes

* Move files under ci directory

* Set CUDA env var to setup cuda drivers

* Fixup and add README

* shellcheck

* Apply review feedback, rename dir and setup files

Co-authored-by: publish-docs.sh <maintainers@solana.com>

ci/setup-new-buildkite-agent/setup-procfs-knobs.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+HERE="$(dirname "$0")"
+
+# shellcheck source=ci/setup-new-buildkite-agent/utils.sh
+source "$HERE"/utils.sh
+
+ensure_env || exit 1
+
+# Setup kernel constants
+cat > /etc/sysctl.d/20-solana-node.conf <<EOF
+
+# Solana networking requirements
+net.core.rmem_default=134217728
+net.core.rmem_max=134217728
+net.core.wmem_default=134217728
+net.core.wmem_max=134217728
+
+# Solana earlyoom setup
+kernel.sysrq=$(( $(cat /proc/sys/kernel/sysrq) | 64 ))
+
+# Allow kernel and CPU perf events
+kernel.perf_event_paranoid=0
+EOF
+