auth-app too slow to get the password

## Describe the bug
Requests going through the auth-app service for authentication are too slow. It seems to depend on the number of tokens created by the user.

## Steps to reproduce
1. Enable auth-app
2. Create a token with the auth-app
3. Perform several operations

## Expected behavior
Operations finish in a reasonable time

## Actual behavior
auth-app takes a lot of time to get the password. Lowest time seems to be around 1 second, and it goes up to 14 seconds. In all the cases I've checked, the `GetAppPassword` operation takes the whole time.

Even considering a heavy workload in the host, the timing seems too focus on that operation.

## Setup
Pretty much default setup, with the auth-app service enabled.

```console
OCIS_XXX=somevalue
OCIS_YYY=somevalue
PROXY_XXX=somevalue
```

## Additional context
* The requests are always using the auth-app token. Oauth isn't being used in the requests.
* The token is used for the admin to impersonate other users
* Tokens are being piled up without being removed. I think I have around 121 tokens active for the admin user.

I guess I need to be more careful with the token creation, but I'm not sure if such amount of active tokens should make the system that slow.