Changes

Fixes #1892

• adds a new environment variable called: PRODUCT_CATALOG_RELOAD_INTERVAL
• reloads the product catalog according to an interval based on the env variable (defaults to 10 seconds)
• mounts the product.json file at run time instead of including it at image build time

This allows the user to change the products without rebuilding the product-catalog service. The products can also be updated after the demo is running. The change also paves the way for reloading the product catalog on a period timer, allowing the product list to be backed by more dynamic sources such as a database.

Finally, this change will require some updates to the Helm chart to load and mount the product list via a ConfigMap.

Merge Requirements

For new features contributions, please make sure you have completed the following
essential items:

• CHANGELOG.md updated to document new feature additions
• Appropriate documentation updates in the docs
• Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure
which docs need to be changed ping the
@open-telemetry/demo-approvers.