Revert "kv: Set default SendNextTimeout to a reasonable value"
Revert "kv: Set default SendNextTimeout to a reasonable value"

This reverts commit f0be19ff11b87ff86f0d1e5cb33c4d1e20d608ef.

I think this change was responsible for the race seen in #6750,
but I haven't been able to reproduce it in a test yet.

glycerine/cockroach,vaibhavarora/cockroach,glycerine/cockroach,cockroachdb/cockroach,maxlang/cockroach,paperstreet/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,veteranlu/cockroach,sunya123/cockroach,vivekmenezes/cockroach,sunya123/cockroach,veteranlu/cockroach,paperstreet/cockroach,petermattis/cockroach,cockroachdb/cockroach,vivekmenezes/cockroach,veteranlu/cockroach,glycerine/cockroach,maxlang/cockroach,petermattis/cockroach,maxlang/cockroach,veteranlu/cockroach,petermattis/cockroach,sunya123/cockroach,veteranlu/cockroach,paperstreet/cockroach,arjun4084346/cockroach,arjun4084346/cockroach,glycerine/cockroach,vaibhavarora/cockroach,sunya123/cockroach,maxlang/cockroach,vaibhavarora/cockroach,maxlang/cockroach,arjun4084346/cockroach,glycerine/cockroach,glycerine/cockroach,veteranlu/cockroach,sunya123/cockroach,vaibhavarora/cockroach,petermattis/cockroach,arjun4084346/cockroach,paperstreet/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,petermattis/cockroach,petermattis/cockroach,arjun4084346/cockroach,veteranlu/cockroach,paperstreet/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,vivekmenezes/cockroach,vaibhavarora/cockroach,maxlang/cockroach,glycerine/cockroach,cockroachdb/cockroach,vivekmenezes/cockroach,paperstreet/cockroach,sunya123/cockroach,vivekmenezes/cockroach,cockroachdb/cockroach,paperstreet/cockroach,sunya123/cockroach,sunya123/cockroach,maxlang/cockroach,petermattis/cockroach,paperstreet/cockroach,petermattis/cockroach,vivekmenezes/cockroach,vivekmenezes/cockroach,maxlang/cockroach,glycerine/cockroach,arjun4084346/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach