fix: fix failed workspaces continuously auto-deleting (#10069)

- Fixes an issue where workspaces that are eligible for auto-deletion
  are retried every tick (1 minute) even if the previous deletion
  transition failed.

  The updated logic only attempts to delete workspaces that previously
  failed once a day (24 hours since last attempt).

coderd/database/modelmethods.go

@@ -367,3 +367,19 @@ func ConvertWorkspaceRows(rows []GetWorkspacesRow) []Workspace {
 func (g Group) IsEveryone() bool {
 	return g.ID == g.OrganizationID
 }
+
+func (p ProvisionerJob) Finished() bool {
+	return p.CanceledAt.Valid || p.CompletedAt.Valid
+}
+
+func (p ProvisionerJob) FinishedAt() time.Time {
+	if p.CompletedAt.Valid {
+		return p.CompletedAt.Time
+	}
+
+	if p.CanceledAt.Valid {
+		return p.CanceledAt.Time
+	}
+
+	return time.Time{}
+}