fix(custom-resources): use loggingFormat instead of deprecated logFormat (#35015)

Use loggingFormat instead of deprecated logFormat in the Provider class

### Issue # (if applicable)
Closes #35002

### Reason for this change
The `logFormat` property in Lambda Function is deprecated and will be removed in the next major release. This change updates the Provider class to use the recommended `loggingFormat` property instead, eliminating deprecation warnings.

### Description of changes
- Updated the Provider class in `provider.ts` to use `loggingFormat` instead of the deprecated `logFormat` property
- Added a test in `provider.test.ts` to verify that no deprecation warnings are emitted when creating a Provider
- Ensured backward compatibility by maintaining the same functionality

This change is minimal and focused on replacing the deprecated property with its recommended alternative. The functionality remains the same, but the code now follows best practices and avoids deprecation warnings.

### Describe any new or updated permissions being added
No new or updated IAM permissions are needed for this change.

### Description of how you validated changes
- Added a unit test that verifies no deprecation warnings are emitted when using the Provider class
- Manually verified that the Provider class still functions correctly with the new property
- Ensured backward compatibility by testing with existing code

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----
*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: pahud

packages/aws-cdk-lib/custom-resources/lib/provider-framework/provider.ts

@@ -324,7 +324,8 @@ export class Provider extends Construct implements ICustomResourceProvider {
       handler: `framework.${entrypoint}`,
       timeout: FRAMEWORK_HANDLER_TIMEOUT,
 
-      logFormat: lambda.LogFormat.JSON,
+      // Using loggingFormat instead of deprecated logFormat which will be removed in the next major release
+      loggingFormat: lambda.LoggingFormat.JSON,
       applicationLogLevelV2: loggingLevel,
       // props.logRetention is deprecated, make sure we only set it if it is actually provided
       // otherwise jsii will print warnings even for users that don't use this directly

packages/aws-cdk-lib/custom-resources/test/provider-framework/provider.test.ts

@@ -365,6 +365,37 @@ test('Log level are set to FATAL by default', () => {
   });
 });
 
+test('uses loggingFormat instead of deprecated logFormat', () => {
+  // GIVEN
+  // Spy on console.warn to check for deprecation warnings
+  // eslint-disable-next-line no-console
+  const warnSpy = jest.spyOn(console, 'warn').mockImplementation(() => { });
+
+  const stack = new Stack();
+  const handler = new lambda.Function(stack, 'MyHandler', {
+    code: new lambda.InlineCode('foo'),
+    handler: 'index.onEvent',
+    runtime: lambda.Runtime.NODEJS_LATEST,
+  });
+
+  try {
+    // WHEN
+    new cr.Provider(stack, 'MyProvider', {
+      onEventHandler: handler,
+    });
+
+    // THEN
+    // Check that no deprecation warnings related to logFormat were emitted
+    const deprecationWarnings = warnSpy.mock.calls
+      .filter(args => typeof args[0] === 'string' && args[0].includes('logFormat is deprecated'));
+
+    expect(deprecationWarnings.length).toBe(0);
+  } finally {
+    // Clean up
+    warnSpy.mockRestore();
+  }
+});
+
 describe('retry policy', () => {
   const stack = new Stack();