Update DEVELOPMENT_MAINTENANCE.md guide

Based off istio's DEVELOPMENT_MAINTENANCE.md and dev-maintenance-template.md

For maintained packages make sure to add that a Big Bang MR will NOT be created. So Closes Issue # needs to be added to end of MRs. Also with Redis make sure to have detailed examples of how to test with Authservice.

Updated our DEVELOPMENT_MAINTENANCE.md guide to fit the new format:

Notices

This section should include information about what updates need to be made to the package. This includes breaking changes from new upgrades, additional configurations needed.

How to Upgrade this Package

This section should describe the necessary upgrade steps outlined for each package. It should include a numbered list with detailed steps regarding the upgrade. Please include screenshots as needed for clarity.

Testing new xxxxxxx Package Version

This section should describe the process of testing the newly upgraded package. It should include a numbered list with detailed steps regarding the new version. Please include screenshots as needed for clarity. Below are the steps need to test each package

• Branch/Tag Config
• Cluster setup
• Deploy BigBang
• Test Values Yaml
• Validation/Testing Steps
• Files That Require Integration Testing

Modifications Made to Upstream Chart

This is a high-level list of modifications that Big Bang has made to the upstream helm chart. You can use this as as cross-check to make sure that no modifications were lost during the upgrade process.

Big Bang Chart Additions

If this package has a number of additions to the upstream helm chart to integrate with other Big Bang capabilities, include like the following:

• Monitoring tools (Prometheus/Grafana)
• Service Mesh (Istio)
• Network Policies
• Helm hook jobs for automating upgrade tasks

Instructions for Integration Testing

See the Big Bang Doc