feat: Add config option to prefer GET request over LIST when using Hashicorp Vault (#8049)

## Summary
Hashicorp Vault prefers a `LIST` HTTP method to be used when fetching
secrets but not all environments will allow custom http methods through
WAFs. This PR adds `N8N_EXTERNAL_SECRETS_PREFER_GET` which when set to
`true` will use GET instead of LIST to fetch secrets.


## Review / Merge checklist
- [x] PR title and summary are descriptive. **Remember, the title
automatically goes into the changelog. Use `(no-changelog)` otherwise.**
([conventions](https://github.com/n8n-io/n8n/blob/master/.github/pull_request_title_conventions.md))

packages/cli/src/ExternalSecrets/externalSecretsHelper.ee.ts

@@ -3,6 +3,7 @@ import config from '@/config';
 import Container from 'typedi';
 
 export const updateIntervalTime = () => config.getEnv('externalSecrets.updateInterval') * 1000;
+export const preferGet = () => config.getEnv('externalSecrets.preferGet');
 
 export function isExternalSecretsEnabled() {
 	const license = Container.get(License);