ci: provide a Docker tag for foundationdb release container on workflow_dispatch

The metadata-action used type=ref,event=tag, which produces no tag on
workflow_dispatch, causing build-push to fail with
"tag is needed when pushing to registry". Add a release_tag input and
build the tag from a RELEASE_TAG env, mirroring container_release_unified.yml.

.github/workflows/container_release_foundationdb.yml

@@ -4,11 +4,19 @@ on:
   push:
     tags:
       - '*'
-  workflow_dispatch: {}
+  workflow_dispatch:
+    inputs:
+      release_tag:
+        description: 'Release tag to publish (e.g. 3.93)'
+        required: true
+        default: ''
 
 permissions:
   contents: read
 
+env:
+  RELEASE_TAG: ${{ github.event_name == 'workflow_dispatch' && github.event.inputs.release_tag || github.ref_name }}
+
 jobs:
 
   build-large-release-container_foundationdb:
@@ -26,7 +34,7 @@ jobs:
           images: |
             chrislusf/seaweedfs
           tags: |
-            type=ref,event=tag,suffix=_large_disk_foundationdb
+            type=raw,value=${{ env.RELEASE_TAG }}_large_disk_foundationdb
           flavor: |
             latest=false
           labels: |