request to 'app/list' mostly responds with '500' preventing login

## Describe the bug
After upgrade to 6.2.0 (also tried 6.3.0) I could not login to the webUI. Digging deeper, the problem seemed to be that the `app/list` endpoint mostly returns `500`
```
{
"code": "SERVER_ERROR",
"message": "error listing supported mime types"
}
```

## Steps to reproduce
1. update to 6.2.0
2. try to login

## Expected behavior
login should work

## Actual behavior
`app/list` endpoint mostly returns `500`

## Setup
Please describe how you started the server and provide a list of relevant environment variables or configuration files.

`docker-compose.yml`:

```yaml
---

services:
ocis:
image: owncloud/ocis-rolling:6.2.0
networks:
ocis-net:
ports:
- "9200:9200"
entrypoint:
- /bin/sh
command: [ "-c", "ocis server" ]
environment:
OCIS_URL: https://${OCIS_DOMAIN:-ocis.in-nepal.de}
OCIS_LOG_LEVEL: ${OCIS_LOG_LEVEL:-warn}
OCIS_LOG_COLOR: "${OCIS_LOG_COLOR:-false}"
OCIS_INSECURE: "${INSECURE:-false}"
OCIS_SHARING_PUBLIC_SHARE_MUST_HAVE_PASSWORD: false
PROXY_HTTP_ADDR: 0.0.0.0:9200
PROXY_TLS: false
OCIS_CACHE_STORE: "nats-js-kv"
#OCIS_CACHE_STORE_NODES: "cache:6379"
OCIS_LOG_FILE: /var/log/ocis/ocis.log
MICRO_REGISTRY_ADDRESS: 127.0.0.1:9233
GATEWAY_GRPC_ADDR: 0.0.0.0:9142
NATS_NATS_HOST: 0.0.0.0
NATS_NATS_PORT: 9233
OCIS_SERVICE_ACCOUNT_ID: "******"
OCIS_SERVICE_ACCOUNT_SECRET: "******"
WEB_OPTION_OPEN_LINKS_WITH_DEFAULT_APP: false
WEB_UI_CONFIG_FILE: /etc/ocis/web.config.json
PROXY_CSP_CONFIG_FILE_LOCATION: /etc/ocis/csp.yaml
restart: always
volumes:
- type: bind
source: /mnt/HC_Volume_32687865/ocis-config
target: /etc/ocis
- type: bind
source: /mnt/HC_Volume_32687865/ocis-data
target: /var/lib/ocis
- type: bind
source: /mnt/HC_Volume_32687865/ocis-logs
target: /var/log/ocis

networks:
ocis-net:
```

`web.config.json`:

```json
{
"server": "https://ocis.in-nepal.de",
"theme": "https://ocis.in-nepal.de/themes/owncloud/theme.json",
"openIdConnect": {
"metadata_url": "https://ocis.in-nepal.de/.well-known/openid-configuration",
"authority": "https://ocis.in-nepal.de",
"client_id": "web",
"response_type": "code",
"scope": "openid profile email"
},
"options": {
"topCenterNotifications": true,
"openLinksWithDefaultApp": false,
"sidebar": {
"shares": {
"showAllOnLoad": true
}
},
"contextHelpersReadMore": true
},
"apps": [
"files",
"text-editor",
"pdf-viewer",
"search",
"external",
"admin-settings",
"ocm",
"webfinger"
]
}
```

## Additional context
log output:
```

{"level":"error","service":"frontend","pkg":"rhttp","traceid":"11466b3708d16b8c58b48306704c67c8","request-id":"1edc56870acc/PIVWDw5yf9-000014","error":"rpc error: code = Unavailable desc = connection error: desc = \"transport: Error while dialing: dial tcp 172.20.0.6:9142: i/o timeout\"","time":"2024-08-21T06:41:01Z","message":"error listing supported mime types"}
{"level":"error","service":"frontend","pkg":"rhttp","traceid":"11466b3708d16b8c58b48306704c67c8","host":"127.0.0.1","method":"GET","uri":"/app/list","url":"/list","proto":"HTTP/1.1","status":500,"size":79,"start":"21/Aug/2024:06:41:01 +0000","end":"21/Aug/2024:06:41:01 +0000","time_ns":505857,"time":"2024-08-21T06:41:01Z","message":"http"}
```