update code to use . instead of / (#432)

## Summary
#398 updated the module path from `"/"` to `"."`, but not all code was
migrated to the new convention, causing frontend API calls to fail when
retrieving joins.

@david-zlai – Can you review the code to ensure it fully aligns with the
new convention?
@sean-zlai – Can you tear down all Docker images and rebuild on this
branch to confirm observability works as expected?

## Checklist
- [ ] Added Unit Tests
- [ ] Covered by existing CI
- [ ] Integration tested
- [ ] Documentation update



<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Refactor**
- Streamlined how configuration names are handled in observability
views. Names are now displayed as originally provided without extra
formatting, ensuring a consistent and straightforward presentation. The
fallback label remains “Unknown” when a name is not available.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: ken-zlai

spark/src/main/scala/ai/chronon/spark/scripts/ObservabilityDemo.scala

@@ -155,13 +155,12 @@ object ObservabilityDemo {
     val name = "dim_user_account_type"
     val window = new Window(10, ai.chronon.api.TimeUnit.HOURS)
 
-    val joinPath = joinName.replaceFirst("\\.", "/")
     logger.info("Looking up current summary series")
-    val maybeCurrentSummarySeries = driftStore.getSummarySeries(joinPath, startTs, endTs, Some(name)).get
+    val maybeCurrentSummarySeries = driftStore.getSummarySeries(joinName, startTs, endTs, Some(name)).get
     val currentSummarySeries = Await.result(maybeCurrentSummarySeries, Duration.create(10, TimeUnit.SECONDS))
     logger.info("Now looking up baseline summary series")
     val maybeBaselineSummarySeries =
-      driftStore.getSummarySeries(joinPath, startTs - window.millis, endTs - window.millis, Some(name))
+      driftStore.getSummarySeries(joinName, startTs - window.millis, endTs - window.millis, Some(name))
     val baselineSummarySeries = Await.result(maybeBaselineSummarySeries.get, Duration.create(10, TimeUnit.SECONDS))
 
     logger.info(s"Current summary series: $currentSummarySeries")