Add expiry to the remote-definitions-provider cache

The airbyte-platform PR template directs contributions here, so filing this as an issue with a ready patch.

**Platform Version:** charts/v2/airbyte 1.1.0 (airbyte-server on main); the cache is unconfigured on all current versions.

## Proposed change

Adds a cache expiry for `remote-definitions-provider` to airbyte-server's application.yml, mirroring the 15s `expire-after-write` that airbyte-cron already configures for the same caches.

## Why

Both airbyte-cron and airbyte-server use `RemoteDefinitionsProvider.getRemoteConnectorRegistry()`, which is `@Cacheable` under the `remote-definitions-provider` cache. airbyte-cron configures that cache with `expire-after-write: 15s`, but airbyte-server does not configure it at all, so the server memoizes its first registry fetch after pod start indefinitely.

Visible effect in the stock UI: on an instance whose server pods have been running for a few days, the connector version information shown in Settings (which is served from `list_latest`) lags behind the definition updates the cron has already applied, until the server pod restarts. Aligning the server's cache configuration with the cron's fixes this with no code change.

## How

One configuration addition under the server's `micronaut.caches` section, matching the cron's existing values. No code changes.

A ready patch is available at https://github.com/airbytehq/airbyte-platform/compare/main...RafPe:airbyte-platform:server-registry-cache-ttl; happy to open it as a PR wherever you prefer.

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**Internal Tracking:** https://github.com/airbytehq/oncall/issues/13248