Update voltha-system-tests builders to 22.04

Signed-off-by: Eric Ball <eball@linuxfoundation.org>
Change-Id: Ia0c28f314844d4948c816ba7c939bf18d0d116f2
diff --git a/jjb/verify/voltha-system-tests.yaml b/jjb/verify/voltha-system-tests.yaml
index a45c619..4a1e44e 100644
--- a/jjb/verify/voltha-system-tests.yaml
+++ b/jjb/verify/voltha-system-tests.yaml
@@ -7,10 +7,10 @@
 
     jobs:
       - 'verify-voltha-system-tests-jobs':
-          build-node: 'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu22.04-basebuild-4c-8g'
           branch-regexp: '{all-branches-regexp}'
       - 'verify-voltha-system-tests-jobs-master':
-          build-node: 'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu22.04-basebuild-4c-8g'
           branch-regexp: '^master$'
       - 'verify-voltha-system-tests-jobs-py312':
           build-node: 'ubuntu24.04-basebuild-4c-8g'
@@ -18,12 +18,12 @@
           override-branch: 'python312-update'
           branch-regexp: '^python312-update$'
       - 'verify-voltha-system-tests-jobs-voltha-2.13':
-          build-node: 'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu22.04-basebuild-4c-8g'
           name-extension: '-voltha-2.13'
           override-branch: 'voltha-2.13'
           branch-regexp: '^voltha-2.13$'
       - 'verify-voltha-system-tests-jobs-voltha-2.11':
-          build-node: 'ubuntu18.04-basebuild-4c-8g'
+          build-node: 'ubuntu22.04-basebuild-4c-8g'
           name-extension: '-voltha-2.11'
           override-branch: 'voltha-2.11'
           branch-regexp: '^voltha-2.11$'