In a large cluster, support bundle can fail with too many open files error

[divolgin]

Bug Description

When running redactors, all redactions are batched together, which causes too many files to be open at the same time

 * failed to run collector "cluster-resources": failed to redact: failed to create redacted result: failed to create temp file: open /var/folders/g2/05ngff7d71gds3_kl24gs0f80000gn/T/replace-465965942: too many open files

Expected Behavior

Support bundle should be collected successfully.

Steps To Reproduce

cat << EOF > spec.yaml
apiVersion: troubleshoot.sh/v1beta2
kind: SupportBundle
metadata:
  name: sample
spec:
  collectors:
    - clusterResources: {}
EOF

kubectl support-bundle spec.yaml

Additional Context

Include the following information.

• Troubleshoot version: built from source at revision 9666679, go version 1.16.6
• Operating system: Mac OS
• Operating system version: Catalina
• Other details that might be helpful in diagnosing the problem: this happened on a cluster with over 300 pods, 1300 jobs, and thousands of other objects, including custom resources.