Fix otel startup bug (chroma-core#1263)

## Description of changes

*Summarize the changes made by this PR.*
 - Improvements & Bug fixes
- Fixes
chroma-core#1260 (comment)
- TL;DR the default `chroma_otel_tracing_granularity` ends up set to
`""` which isn't a valid enum value.
 - New functionality
	 - None

## Test plan
*How are these changes tested?*

- CI
- The `docker-compose` startup flow works now

## Documentation Changes
*Are all docstrings for user-facing APIs updated if required? Do we need
to make documentation changes in the [docs
repository](https://github.com/chroma-core/docs)?*

chromadb/config.py

@@ -179,7 +179,7 @@ def chroma_server_auth_credentials_file_non_empty_file_exists(
     chroma_otel_collection_endpoint: Optional[str] = ""
     chroma_otel_service_name: Optional[str] = "chromadb"
     chroma_otel_collection_headers: Dict[str, str] = {}
-    chroma_otel_granularity: Optional[str] = "none"
+    chroma_otel_granularity: Optional[str] = None
 
     allow_reset: bool = False
 

chromadb/telemetry/opentelemetry/__init__.py

@@ -49,7 +49,11 @@ def __init__(self, system: System):
             system.settings.chroma_otel_service_name,
             system.settings.chroma_otel_collection_endpoint,
             system.settings.chroma_otel_collection_headers,
-            OpenTelemetryGranularity(system.settings.chroma_otel_granularity),
+            OpenTelemetryGranularity(
+                system.settings.chroma_otel_granularity
+                if system.settings.chroma_otel_granularity
+                else "none"
+            ),
         )