vmagent: raise kubernetes-apiservers max_scrape_size to 64MiB (#517)

The kubernetes-apiservers job reports up=0 on every target because the apiserver /metrics response exceeds vmagent's default 16MiB scrape size limit.

- set max_scrape_size: 64MiB on the kubernetes-apiservers job only

Reviewed-on: #517
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/base/observability/vmagent.yaml

@@ -37,6 +37,7 @@ spec:
       static_configs:
         - targets: ["localhost:8429"]
     - job_name: "kubernetes-apiservers"
+      max_scrape_size: 64MiB
       kubernetes_sd_configs:
         - role: endpoints
       scheme: https