Allow customer to manipulate auto-insstrumention both enable/disable (#107)

*Description of changes:*
Fully support NodeJS enable/disable configuration
```
if both OTEL_NODE_ENABLED_INSTRUMENTATIONS and OTEL_NODE_DISABLED_INSTRUMENTATIONS are not configured, set OTEL_NODE_ENABLED_INSTRUMENTATIONS="aws-sdk,aws-lambda"
else if OTEL_NODE_ENABLED_INSTRUMENTATIONS is configure and OTEL_NODE_DISABLED_INSTRUMENTATIONS is not, append OTEL_NODE_ENABLED_INSTRUMENTATIONS with "aws-lambda"
else if both OTEL_NODE_ENABLED_INSTRUMENTATIONS and OTEL_NODE_DISABLED_INSTRUMENTATIONS are configured, append OTEL_NODE_ENABLED_INSTRUMENTATIONS with "aws-lambda"
else do nothing
```

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copy, and redistribute this contribution, under the terms of your
choice.

Author: mxiamxia

lambda-layer/packages/layer/scripts/otel-instrument

@@ -43,9 +43,22 @@ if [ -z "${OTEL_EXPORTER_OTLP_PROTOCOL}" ]; then
     export OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
 fi
 
-# - If OTEL_NODE_ENABLED_INSTRUMENTATIONS is not set by user, use default instrumentation
-if [ -z "${OTEL_NODE_ENABLED_INSTRUMENTATIONS}" ]; then
-    export OTEL_NODE_ENABLED_INSTRUMENTATIONS="aws-lambda,aws-sdk"
+# If both OTEL_NODE_ENABLED_INSTRUMENTATIONS and OTEL_NODE_DISABLED_INSTRUMENTATIONS are not configured,
+# set OTEL_NODE_ENABLED_INSTRUMENTATIONS="aws-sdk,aws-lambda"
+if [ -z "${OTEL_NODE_ENABLED_INSTRUMENTATIONS}" ] && [ -z "${OTEL_NODE_DISABLED_INSTRUMENTATIONS}" ]; then
+    export OTEL_NODE_ENABLED_INSTRUMENTATIONS="aws-sdk,aws-lambda"
+
+# Else if OTEL_NODE_ENABLED_INSTRUMENTATIONS is configured and OTEL_NODE_DISABLED_INSTRUMENTATIONS is not,
+# append OTEL_NODE_ENABLED_INSTRUMENTATIONS with "aws-lambda"
+elif [ -n "${OTEL_NODE_ENABLED_INSTRUMENTATIONS}" ] && [ -z "${OTEL_NODE_DISABLED_INSTRUMENTATIONS}" ]; then
+    export OTEL_NODE_ENABLED_INSTRUMENTATIONS="${OTEL_NODE_ENABLED_INSTRUMENTATIONS},aws-lambda"
+
+# Else if both OTEL_NODE_ENABLED_INSTRUMENTATIONS and OTEL_NODE_DISABLED_INSTRUMENTATIONS are configured,
+# append OTEL_NODE_ENABLED_INSTRUMENTATIONS with "aws-lambda"
+elif [ -n "${OTEL_NODE_ENABLED_INSTRUMENTATIONS}" ] && [ -n "${OTEL_NODE_DISABLED_INSTRUMENTATIONS}" ]; then
+    export OTEL_NODE_ENABLED_INSTRUMENTATIONS="${OTEL_NODE_ENABLED_INSTRUMENTATIONS},aws-lambda"
+
+# Else do nothing
 fi
 
 # - Set the service name