Remove unused constants (#350)

## Problem

I noticed there are a few constants defined that are not currently being
used anywhere.

## Solution

- Search in codebase to confirm these are no longer in use.
- Remove them.

## Type of Change

- [x] Chore (cleanup dead code)

## Test Plan

See tests still pass.

Author: jhamon

pinecone/utils/constants.py

@@ -8,20 +8,6 @@
 MAX_ID_LENGTH = int(os.getenv("PINECONE_MAX_ID_LENGTH", default="64"))
 
 REQUEST_ID: str = "request_id"
-CLIENT_VERSION_HEADER = "X-Pinecone-Client-Version"
-
-
-class NodeType(str, enum.Enum):
-    STANDARD = "STANDARD"
-    COMPUTE = "COMPUTE"
-    MEMORY = "MEMORY"
-    STANDARD2X = "STANDARD2X"
-    COMPUTE2X = "COMPUTE2X"
-    MEMORY2X = "MEMORY2X"
-    STANDARD4X = "STANDARD4X"
-    COMPUTE4X = "COMPUTE4X"
-    MEMORY4X = "MEMORY4X"
-
 
 CLIENT_VERSION = __version__
 CLIENT_ID = f"python-client-{CLIENT_VERSION}"