fix #4895: scheduled jobs: ignore task-log not found error

Use the job start-time as end-time when it's stuck in the
`JobState::Starting` state, no active working is running and the task
log of the last run doesn't exists.

A user experienced a power loss, which left a GC job in the `Started`
state, but the task log did not exist. This breaks the schedule and no
following GC runs. Now, the error is simply ignored and a new gc job
is started on the next occurrence.

Signed-off-by: Gabriel Goller <g.goller@proxmox.com>

src/server/jobstate.rs

@@ -198,8 +198,9 @@ impl JobState {
                         .map_err(|err| format_err!("error parsing upid: {err}"))?;
 
                     if !worker_is_active_local(&parsed) {
-                        let state = upid_read_status(&parsed)
-                            .map_err(|err| format_err!("error reading upid log status: {err}"))?;
+                        let state = upid_read_status(&parsed).unwrap_or(TaskState::Unknown {
+                            endtime: parsed.starttime,
+                        });
 
                         Ok(JobState::Finished {
                             upid,