[ENH] - Use GitHub secrets instead of Vault

[marcelovilla]

Feature description

We're currently relying on Vault, hosted on HashiCorp Cloud Platform, to read secrets for our GHA workflows. For example:

nebari/.github/workflows/test_aws_integration.yaml

Lines 61 to 70 in 855aa14

	- name: Retrieve secret from Vault
	uses: hashicorp/[email protected]
	with:
	method: jwt
	url: "https://quansight-vault-public-vault-b2379fa7.d415e30e.z1.hashicorp.cloud:8200"
	namespace: "admin/quansight"
	role: "repository-nebari-dev-nebari-role"
	secrets: |
	kv/data/repository/nebari-dev/nebari/amazon_web_services/nebari-dev-ci role_name | AWS_ROLE_ARN;
	kv/data/repository/nebari-dev/nebari/cloudflare/[email protected]/nebari-dev-ci token | CLOUDFLARE_TOKEN;

In the previous months, our Vault configuration has broken, resulting in failing GHA jobs when trying to read secrets. Here's a recent example: https://github.com/nebari-dev/nebari/actions/runs/11628815929/job/32384643624#step:5:32

I think we could simplify our secret management logic and use GitHub secrets instead.

Value and/or benefit

Migrating from Vault to GitHub secrets would reduce the maintenance burden and avoid jobs failing because of a broken Vault configuration.

Anything else?

No response

[Adam-D-Lewis]

We talked about this in the maintainers meeting this morning and were in favor of this change.