[CI] Update label in schedule daily job definition as part of the aut…

…omation (elastic#10722)

Update label step in the schedule daily job using updatecli so it
gets updated with the latest snapshot version (major and minor)
accordingly with the STACK_VERSION value.

.github/workflows/updatecli/updatecli.d/bump-latest-snapshot-version.yml

@@ -31,6 +31,16 @@ sources:
     spec:
       file: https://storage.googleapis.com/artifacts-api/snapshots/main.json
       key: .version
+  latestSnapshotMajorMinor:
+    name: Get latest snapshort major and minor
+    kind: json
+    spec:
+      file: https://storage.googleapis.com/artifacts-api/snapshots/main.json
+      key: .version
+    transformers:
+      - findsubmatch:
+          pattern: '(^\d+\.\d+)\.[^\s]+$'
+          captureindex: 1
 
 targets:
   update-snapshot:
@@ -42,3 +52,13 @@ targets:
       file: '.buildkite/pipeline.schedule-daily.yml'
       matchpattern: '(STACK_VERSION:) 8\.[^\s]*\.[^\s]*'
       replacepattern: '$1 {{ source "latestSnapshot" }}'
+
+  update-snapshot-label:
+    name: '[updatecli] Update latest snapshot label step to {{ source "latestSnapshotMajorMinor" }}'
+    kind: file
+    sourceid: latestSnapshotMajorMinor
+    scmid: default
+    spec:
+      file: '.buildkite/pipeline.schedule-daily.yml'
+      matchpattern: '(Stack Version) v8\.\d+"'
+      replacepattern: 'Stack Version v{{ source "latestSnapshotMajorMinor" }}"'