When using a matrix strategy the actions fails in the post step

### Describe the Issue

When using a matrix strategy to run the job multiple times the actions post step fails all but once because it can not find the initial reaction that has been removed already by some other matrix run.

### Action Configuration

```yaml
jobs:
something:
strategy:
matrix:
runs:
- a
- b
steps:
- name: Check command in comment
id: command
uses: github/command@v2
with:
command: .plan
allowed_contexts: "pull_request"
```

### Relevant Actions Log Output

```
2025-06-25T07:24:32.1785017Z ##[error]HttpError: Not Found - https://docs.github.com/enterprise-server@3.16/rest/reactions/reactions#delete-an-issue-comment-reaction
at /__w/_actions/actions/command/v2/node_modules/@octokit/core/node_modules/@octokit/request/dist-node/index.js:125:1
at processTicksAndRejections (node:internal/process/task_queues:95:5)
at postReactions (/__w/_actions/actions/command/v2/src/functions/post-reactions.js:8:1)
at post (/__w/_actions/actions/command/v2/src/functions/post.js:65:1)
2025-06-25T07:24:32.1802743Z ##[error]Not Found - https://docs.github.com/enterprise-server@3.16/rest/reactions/reactions#delete-an-issue-comment-reaction
```

### Extra Information

_No response_

Start with src/functions/post-reactions.js and src/functions/post.js, the files named in the action log, and reproduce the failure using the matrix configuration in the issue. Trace how each matrix run finds and removes the initial reaction. Done means the post step no longer reports a Not Found error when multiple matrix runs process the same comment reaction.

Scritto dal modello di indicizzazione a partire dal testo della issue.