[currency] - fix metric name

[puckpuck]

Changes

We broke the metric name in #1378. This fixes that name and sets it to app.currency.counter.total as it was before.

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.