use logging instead of prints (#499)

# What does this PR do?

This PR moves all print statements to use logging. Things changed:
- Had to add `await start_trace("sse_generator")` to server.py to
actually get tracing working. else was not seeing any logs
- If no telemetry provider is provided in the run.yaml, we will write to
stdout
- by default, the logs are going to be in JSON, but we expose an option
to configure to output in a human readable way.

llama_stack/providers/remote/memory/pgvector/pgvector.py

@@ -4,6 +4,7 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+import logging
 from typing import List, Tuple
 
 import psycopg2
@@ -24,6 +25,8 @@ from llama_stack.providers.utils.memory.vector_store import (
 
 from .config import PGVectorConfig
 
+log = logging.getLogger(__name__)
+
 
 def check_extension_version(cur):
     cur.execute("SELECT extversion FROM pg_extension WHERE extname = 'vector'")
@@ -124,7 +127,7 @@ class PGVectorMemoryAdapter(Memory, MemoryBanksProtocolPrivate):
         self.cache = {}
 
     async def initialize(self) -> None:
-        print(f"Initializing PGVector memory adapter with config: {self.config}")
+        log.info(f"Initializing PGVector memory adapter with config: {self.config}")
         try:
             self.conn = psycopg2.connect(
                 host=self.config.host,
@@ -138,7 +141,7 @@ class PGVectorMemoryAdapter(Memory, MemoryBanksProtocolPrivate):
 
             version = check_extension_version(self.cursor)
             if version:
-                print(f"Vector extension version: {version}")
+                log.info(f"Vector extension version: {version}")
             else:
                 raise RuntimeError("Vector extension is not installed.")
 
@@ -151,9 +154,7 @@ class PGVectorMemoryAdapter(Memory, MemoryBanksProtocolPrivate):
             """
             )
         except Exception as e:
-            import traceback
-
-            traceback.print_exc()
+            log.exception("Could not connect to PGVector database server")
             raise RuntimeError("Could not connect to PGVector database server") from e
 
     async def shutdown(self) -> None: