Change VSPC plugin to work a bit better with certain attribute changes.

vspc_backup_checks/2.3/local/lib/python3/cmk_addons/plugins/vspc_backup_checks/libexec/agent_vspc_backup_checks

@@ -196,6 +196,9 @@ def process(mAgents, bAgents, jobs, managed):
             if failureMessage:
                 # We use 2.2 here to give wiggle room for jobs to complete if
                 # they take longer than expected.
+                #
+                # NB: we assume here that lastEndTime was set if there's a
+                # failureMessage.
                 results[host].append({
                     "status":  CRIT if daysSinceLastRun > 2.2 else WARN,
                     "message": f"Backup agent {bAgentId} job {jobId} failed {daysSinceLastRun:.1f} days ago: {failureMessage}"
@@ -209,13 +212,7 @@ def process(mAgents, bAgents, jobs, managed):
                 })
                 continue
 
-            if not daysSinceLastRun:
-                results[host].append({
-                    "status":  OK,
-                    "message": f"Backup agent {bAgentId} is healthy; no backups yet."
-                })
-                continue
-
+            if daysSinceLastRun is not None:
                 # We use 1.2 & 2.2 here to give wiggle room for jobs to complete if
                 # they take longer than expected.
                 if daysSinceLastRun > 2.2: