fix: handle config-reloader dir watch remove events

[immanuwell]

tiny fix in config-reloader.

when a watched file gets removed from a rules dir, the watcher skips remove events, so it doesnt reload. if a target dir is used, the stale file sticks around there too, kinda meh.

fix:

• process remove events like normal dir changes
• add tests for delete reload and target dir cleanup

repro:

1. start config-reloader and watch a dir with rules.yaml
2. delete rules.yaml
3. before this patch, no reload is triggered
4. if a target dir is configured, the stale file stays there too

checks:

• make lint
• make manifests
• make api-gen
• make docs
• go test ./cmd/config-reloader
• go test $(go list ./... | grep -v /e2e)

[cubic-dev-ai]

No issues found across 2 files

_{Re-trigger cubic}