Delete .github/workflows/claude-review.yml (#5314)

# Description

Remove the claude-review.yml.

It needs some iteration. Fires too frequently. It's noisy and too
verbose. There's no way to silence it on long iterative PRs. And we
should iterate on the pull request target usage as well.

In the interim we've enabled Codex review, which does not have many of
these downsides.

The shared claude-review workflow we can keep iterating on, and test it
on one repo before bringing it to a bunch and creating too much noise:
- stellar/actions#103

cc @anupsdf

# Checklist
- [ ] Reviewed the
[contributing](https://github.com/stellar/stellar-core/blob/master/CONTRIBUTING.md#submitting-changes)
document
- [ ] Rebased on top of master (no merge commits)
- [ ] Ran `clang-format` v8.0.0 (via `make format` or the Visual Studio
extension)
- [ ] Compiles
- [ ] Ran all tests
- [ ] If change impacts performance, include supporting evidence per the
[performance
document](https://github.com/stellar/stellar-core/blob/master/performance-eval/performance-eval.md)

Author: leighmcculloch