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

- 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

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jchrostek-dd

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) {

integration-tests/lambda/base-dotnet/Function.cs

@@ -1,4 +1,3 @@
 bin/
 obj/
 *.user
-*.suo