L2 Construct for AWS::ObservabilityAdmin::OrganizationCentralizationRule

## Description

Create L2 CDK constructs for ObservabilityAdmin OrganizationCentralizationRule [[L1](https://github.com/aws/aws-cdk/tree/main/packages/aws-cdk-lib/aws-observabilityadmin)].

## Roles

| Role | User
|---------------------|------------------------------
| Proposed by | @jsicheng
| Author(s) | @jsicheng
| API Bar Raiser | TBD
| Stakeholders | @sidbhate

> See [RFC Process](https://github.com/aws/aws-cdk-rfcs#rfc-process) for details

## Workflow

- [x] Tracking issue created (label: `status/proposed`)
- [ ] API bar raiser assigned (ping us at [#aws-cdk-rfcs](https://cdk-dev.slack.com/archives/C025ZFGMUCD) if needed)
- [ ] Kick off meeting
- [ ] RFC pull request submitted (label: `status/review`)
- [ ] Community reach out (via Slack and/or Twitter)
- [ ] API signed-off (label `status/api-approved` applied to pull request)
- [ ] Final comments period (label: `status/final-comments-period`)
- [ ] Approved and merged (label: `status/approved`)
- [ ] Execution plan submitted (label: `status/planning`)
- [ ] Plan approved and merged (label: `status/implementing`)
- [ ] Implementation complete (label: `status/done`)

---

> Author is responsible to progress the RFC according to this checklist, and
apply the relevant labels to this issue so that the RFC table in README gets
updated.

Start by reviewing the linked L1 package at packages/aws-cdk-lib/aws-observabilityadmin and the RFC Process. Follow the checklist from API bar raiser assignment through RFC review, approval, planning, and implementation. Done means the RFC workflow reaches implementation complete and the corresponding L2 construct work is complete.

Written by the indexing model from the issue text.