fix: don't abort kind-dev-env.sh on macOS when PROM_ENABLED=true

[sudoalok]

What this does

Stops PROM_ENABLED=true make env-dev-kind from aborting on macOS.

The Prometheus pre-flight check in scripts/kind-dev-env.sh reads
/proc/sys/fs/inotify/max_user_instances, a Linux-only path. On macOS that
read fails and, under set -eo pipefail, the failed cat kills the whole
script before the cluster is ever created.

This falls back to a passing value when the path is absent, so the host-side
check degrades gracefully off-Linux. On Linux the behavior is unchanged.

 if [ "${PROM_ENABLED}" == "true" ]; then
-  INOTIFY_INSTANCES=$(cat /proc/sys/fs/inotify/max_user_instances)
+  INOTIFY_INSTANCES=$(cat /proc/sys/fs/inotify/max_user_instances 2>/dev/null || echo 512)

[elevran]

@sudoalok please fix the conflict

[sudoalok]

thanks @elevran - looks like this was superseded. #1654 already merged the same macOS fix on main (guards the /proc read with -r plus a node-side check for the VM case), which covers what this PR did and more. nothing left for this one to add, so closing as superseded by #1654

[elevran]

closing as superseded by #1654