[Tarantool-patches] [PATCH vshard 3/7] test: disable router discovery for some tests

[Vladislav Shpilevoy]

Thanks for the review!

>> @@ -49,13 +51,13 @@ util.collect_timeouts(rs1)
>>       ok: 0
>>       timeout: 0.5
>>     - fail: 0
>> -    ok: 1
>> +    ok: 0
>>       timeout: 0.5
>>   ...
>>   util.collect_timeouts(rs2)
>>   ---
>>   - - fail: 0
>> -    ok: 1
>> +    ok: 0
>>       timeout: 0.5
>>     - fail: 0
>>       ok: 0
>> @@ -74,7 +76,7 @@ util.collect_timeouts(rs1)
>>       ok: 0
>>       timeout: 0.5
>>     - fail: 0
>> -    ok: 9
>> +    ok: 8
>>       timeout: 0.5
>>   ...
>>   _ = rs1:callrw('echo')
>> @@ -86,7 +88,7 @@ util.collect_timeouts(rs1)
>>       ok: 0
>>       timeout: 0.5
>>     - fail: 0
>> -    ok: 1
>> +    ok: 9
>>       timeout: 0.5
>>   ...
> 
> Sorry for maybe quite stupid question, but why does it quite significantly increase?
> ```
> net_sequential_ok - count of sequential success requests to the replica
> ```

This is because the value is truncated to 1, when becomes >= 10. Since
there is no discovery, this makes number of successful requests decremented.
Before the patch value was 1. So 1 - 1 = 0, this brings the counter to its
previous round, where it ended up being 9.

After 10 the counter is truncated, because the only thing which matters -
did it manage to make 10 successful requests in a row or not. If it did,
the timeout is decreased. If it managed, then can start from 1 again.