[self-hosted] Add a UBI image variant for the combined server (#7953)

* [self-hosted] Add a UBI image variant for the combined server

OpenShift and other Red Hat environments expect UBI-based images that run
as an arbitrary non-root UID. The proxy and rootless client already ship
-ubi variants; this adds the same for netbird-server, published as
<version>-ubi and ubi-latest for amd64 and arm64.

* [self-hosted] Check the license output path before creating temp files

The existing-output exit ran before the cleanup trap was registered, so it
left the two mktemp files behind.

* [self-hosted] Certify the netbird-server UBI image

Adds netbird-server to the Red Hat certification components. Its Partner
Connect component ID goes in the REDHAT_CERT_ID_NETBIRD_SERVER repository
variable.

.goreleaser.yaml

@@ -511,6 +511,41 @@ dockers_v2:
        "org.opencontainers.image.revision": "{{.FullCommit}}"
        "org.opencontainers.image.source": "{{.GitURL}}"
        "maintainer": "dev@netbird.io"
+   - id: netbird-server-ubi
+     disable: "{{ .Env.SKIP_DOCKER_PUSH }}"
+     ids:
+       - netbird-server
+     images:
+       - netbirdio/netbird-server
+       - ghcr.io/netbirdio/netbird-server
+     tags:
+       - "{{ .Version }}-ubi"
+       - "{{ if eq .Env.SKIP_PUBLISH \"false\" }}ubi-latest{{ end }}"
+     dockerfile: combined/Dockerfile.ubi
+     platforms:
+       - linux/amd64
+       - linux/arm64
+     build_args:
+       VERSION: "{{ .Version }}"
+       RELEASE: "{{ .Timestamp }}"
+     hooks:
+       pre:
+         - cmd: 'sh combined/collect-licenses.sh "{{ .ContextDir }}/licenses" amd64 arm64'
+           env:
+             - GOOS=linux
+             - CGO_ENABLED=1
+     labels:
+       "org.opencontainers.image.created": "{{.Date}}"
+       "org.opencontainers.image.version": "{{.Version}}"
+       "org.opencontainers.image.revision": "{{.FullCommit}}"
+       "org.opencontainers.image.source": "{{.GitURL}}"
+     annotations:
+       "org.opencontainers.image.created": "{{.Date}}"
+       "org.opencontainers.image.title": "{{.ProjectName}}"
+       "org.opencontainers.image.version": "{{.Version}}"
+       "org.opencontainers.image.revision": "{{.FullCommit}}"
+       "org.opencontainers.image.source": "{{.GitURL}}"
+       "maintainer": "dev@netbird.io"
    - id: netbird-proxy
      disable: "{{ .Env.SKIP_DOCKER_PUSH }}"
      ids: