feat(core): custom resources deprecate logRetention in favor of logGroup (#28783)

In #28737 we have deprecated `logRetention` in favor of `logGroup`. Some custom resources have made the `logRetention` property part of their own API and are now emitting deprecation warnings with no way forward to resolve them. So we are now also deprecating `logRetention` for any custom resources.

Migrating log groups for custom resource would follow the same steps as outline in #28737. Given that custom resource logging is for debugging purposes and there are no guarantees about the output format, it should be possible to simply replace `logRetention` with a simple `logGroup` in most cases:

```ts
const awsCustom1 = new cr.AwsCustomResource(this, 'API1', {
  // Replace this
  logRetention: logs.RetentionDays.ONE_WEEK,
  // with
  logGroup: new logs.LogGroup(this, 'AwsCustomResourceLogs', {
    retention: logs.RetentionDays.ONE_WEEK,
  }),
});
```
Fixes #28806
Fixes #28809
Related to #28737

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Author: mrgrain