Vault: api error: status code 400: error configuring token validator: keyset configuration error

I am having issues with Gitlab CI integration in my Vault instance.
On May 14th, Gitlab deprecated the `CI_JOB_JWT` and on May 15th I started to face the following error while my CI jobs try to authenticate with the JWT token signed by gitlab.com:
```
Using "vault" secret resolver...
ERROR: Job failed (system failure): resolving secrets:
initializing Vault service: preparing authenticated client:
authenticating Vault client:
writing to Vault: api error:
status code 400:
error configuring token validator:
keyset configuration error:
Get "https://gitlab.com/.well-known/openid-configuration": dial tcp 172.65.251.78:443: i/o timeout
```
My vault gitlab role looks like this:
```
vault read auth//config

Key Value
bound_issuer https://gitlab.com
default_role
jwks_ca_pem
jwks_url
jwt_supported_algs []
jwt_validation_pubkeys []
namespace_in_state true
oidc_client_id
oidc_discovery_ca_pem
oidc_discovery_url https://gitlab.com
oidc_response_mode
oidc_response_types []
provider_config {}
```
Here is my CI configuration:
```YAML
variables:
VAULT_SERVER_URL: "https://"
VAULT_AUTH_PATH: ""
[...]
tests:
id_tokens:
VAULT_ID_TOKEN:
aud: https://gitlab.com
secrets:
SECRET:
vault: @
token: $VAULT_ID_TOKEN
file: false
```
Gitlab is recommending id_tokens since a long ago as the desired way of authenticating.
IMPORTANT: I am not using the `CI_JOB_JWT` anywhere.

Based on the error, is it possible to actually figure out what is wrong with the JWT auth plugin?

Start by tracing the JWT/OIDC authentication path that configures the token validator and attempts discovery at GitLab's .well-known/openid-configuration endpoint. Reproduce the reported timeout and compare it with the displayed auth configuration; done means identifying whether the failure is in the plugin or external connectivity/configuration and documenting the diagnosis.

Written by the indexing model from the issue text.