refactor(integration-tests): consolidate lambda code and test structure (#1102)

## Overview
- Some refactoring to cleanup the integration test code, will make it
easier for some future changes I plan on making (adding more
comprehensive tests)
- No change to actual extension code.

## Summary

- Rename `base` stack to `on-demand` for clearer naming
- Create shared lambda handlers (`default-*`) used by on-demand, lmi,
and snapstart stacks
- Refactor tests to use `describe.each` pattern for iterating over
runtimes
- Add new test utilities (`default.ts`, `invoke.ts`) for cleaner test
organization
- Remove duplicate per-stack lambda code in favor of shared handlers

This refactoring consolidates ~20 duplicate lambda handler files into 4
shared handlers (one per runtime), making the test infrastructure easier
to maintain and extend.

## Test plan

- [x] Deployed on-demand stack to sandbox account
- [x] Ran `on-demand.test.ts` - all 40 tests passed
- [x] CI checks

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: jchrostek-dd

.gitlab/datasources/test-suites.yaml

@@ -1,5 +1,5 @@
 test_suites:
-  - name: base
+  - name: on-demand
   - name: otlp
   - name: snapstart
   - name: lmi

integration-tests/bin/app.ts

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
 import 'source-map-support/register';
 import * as cdk from 'aws-cdk-lib';
-import {Base} from '../lib/stacks/base';
+import {OnDemand} from '../lib/stacks/on-demand';
 import {Otlp} from '../lib/stacks/otlp';
 import {Snapstart} from '../lib/stacks/snapstart';
 import {LambdaManagedInstancesStack} from '../lib/stacks/lmi';
@@ -22,7 +22,7 @@ const identifier = getIdentifier();
 new CapacityProviderStack(app, `integ-default-capacity-provider`, {env});
 
 const stacks = [
-    new Base(app, `integ-${identifier}-base`, {
+    new OnDemand(app, `integ-${identifier}-on-demand`, {
         env,
     }),
     new Otlp(app, `integ-${identifier}-otlp`, {

integration-tests/config.ts

@@ -3,6 +3,15 @@ import * as os from 'os';
 export const ACCOUNT = process.env.CDK_DEFAULT_ACCOUNT || process.env.AWS_ACCOUNT_ID;
 export const REGION = process.env.CDK_DEFAULT_REGION || process.env.AWS_REGION || 'us-east-1';
 
+// Default wait time for Datadog to index logs and traces after Lambda invocation
+export const DEFAULT_DATADOG_INDEXING_WAIT_MS = 5 * 60 * 1000; // 5 minutes
+
+// Extended wait time for async invocations (SQS, SNS) - need more time for message processing
+export const ASYNC_DATADOG_INDEXING_WAIT_MS = 90 * 1000; // 90 seconds
+
+// Extended wait time for tests that need more time (e.g., OTLP tests)
+export const DATADOG_INDEXING_WAIT_5_MIN_MS = 5 * 60 * 1000; // 5 minutes
+
 
 export function getIdentifier(): string {
   if (process.env.IDENTIFIER) {