expand system.status_reason to 4000

There's no reason to restrict the length of this field (it's not
indexed) and longer values may be useful in some cases.

Change-Id: I45608bb4b91792178d52da170db9f4c0b9fdbd4b
validate length of condition reports

Bug: 980352
Change-Id: Iaa0ced62a3c46f3e9634cc6fc13c8669c008e72a