[CT-3494] Deprecate the `core-triage` action

### Housekeeping

- [X] I am a maintainer of actions

### Short description

This action might not be in use any longer. If so, we can deprecate it as low-hanging tech debt.

One benefit is reducing noise in cases where the action doesn't run successfully.

### Acceptance criteria

1. Confirm will all relevant stakeholders (PMs, DX, EMs for Core+Adapters) that this action is no longer in use
1. Remove the files added within [#27](https://github.com/dbt-labs/actions/pull/27):
- remove `.github/workflows/core-triage.yml`
- remove [`scripts`](https://github.com/dbt-labs/actions/tree/main/scripts) directory:
- `scripts/core-triage/graphql_queries.py`
- `scripts/core-triage/project.py`
- `requirements.txt`
- `README.md`

### Impact to Other Teams

It is possible that someone among PMs, DX, EMs for Core+Adapters is using [this](https://github.com/orgs/dbt-labs/projects/22/views/5) view within a larger GitHub project board, so we'd just need to check first prior to merge.

### Context

https://dbt-labs.slack.com/archives/C044WU55X7Y/p1702489398282579

First review the linked project-board view and Slack context, then confirm with the listed PM, DX, and EM stakeholders that core-triage is unused. Remove .github/workflows/core-triage.yml and the listed scripts/core-triage files, requirements.txt, and README.md; done means the stakeholders have confirmed deprecation and those files are gone.

Written by the indexing model from the issue text.