kit/cli helpers silently drop config/env variables that can't be parsed to the expected type

This behavior can cause user frustration when `influxd` seemingly ignores user inputs, and it's especially dangerous since there's no visible signal when it happens.

Instead of silently dropping bad config/env, we should fail fast. This will need to be clearly communicated in the release notes so users who have had bad config floating around know what's going on after they upgrade and start seeing failures.

NOTE: This might be cleaner to do after #20491

Start by tracing the kit/cli helpers responsible for parsing configuration and environment variables, and review the dependency on issue #20491. Confirm the current behavior for values that cannot be parsed, then make failures visible and update the release notes to communicate the change.

Written by the indexing model from the issue text.