Enable http instrumentations for lambda (#306)

*Description of changes:*
Enabling popular Python httpclient libraries in order to fix the broken
xray propagation issue when calling downstream APIGW in Lambda layer.

Performance testing results:
https://quip-amazon.com/asqwA9QvcfjI/Performance-Testing-Enabled-Instrumentations-in-Lambda-Layer

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: liustve

lambda-layer/src/otel-instrument

@@ -94,6 +94,9 @@ fi
 
 export LAMBDA_RESOURCE_ATTRIBUTES="cloud.region=$AWS_REGION,cloud.provider=aws,faas.name=$AWS_LAMBDA_FUNCTION_NAME,faas.version=$AWS_LAMBDA_FUNCTION_VERSION,faas.instance=$AWS_LAMBDA_LOG_STREAM_NAME,aws.log.group.names=$AWS_LAMBDA_LOG_GROUP_NAME";
 
+if [ -z ${OTEL_PROPAGATORS} ]; then
+    export OTEL_PROPAGATORS="xray,tracecontext,b3,b3multi"
+fi
 
 if [ -z "${OTEL_AWS_APPLICATION_SIGNALS_ENABLED}" ]; then
     export OTEL_AWS_APPLICATION_SIGNALS_ENABLED="true";
@@ -126,7 +129,7 @@ fi
 # - Enable botocore instrumentation by default
 
 if [ -z ${OTEL_PYTHON_DISABLED_INSTRUMENTATIONS} ]; then
-    export OTEL_PYTHON_DISABLED_INSTRUMENTATIONS="aio-pika,aiohttp-client,aiohttp-server,aiopg,asgi,asyncio,asyncpg,boto,boto3,cassandra,celery,confluent_kafka,dbapi,django,elasticsearch,falcon,fastapi,flask,grpc_client,grpc_server,grpc_aio_client,grpc_aio_server,httpx,jinja2,kafka,logging,mysql,mysqlclient,pika,psycopg,psycopg2,pymemcache,pymongo,pymysql,pyramid,redis,remoulade,requests,sklearn,sqlalchemy,sqlite3,starlette,system_metrics,threading,tornado,tortoiseorm,urllib,urllib3,wsgi"
+    export OTEL_PYTHON_DISABLED_INSTRUMENTATIONS="aio-pika,aiohttp-client,aiohttp-server,aiopg,asgi,asyncio,asyncpg,boto,boto3,cassandra,celery,confluent_kafka,dbapi,django,elasticsearch,falcon,fastapi,flask,grpc_client,grpc_server,grpc_aio_client,grpc_aio_server,httpx,jinja2,kafka,logging,mysql,mysqlclient,pika,psycopg,psycopg2,pymemcache,pymongo,pymysql,pyramid,redis,remoulade,requests,sklearn,sqlalchemy,sqlite3,starlette,system_metrics,threading,tornado,tortoiseorm,wsgi"
 fi
 export OTEL_PYTHON_DISABLED_INSTRUMENTATIONS="$OTEL_PYTHON_DISABLED_INSTRUMENTATIONS,aws-lambda";