Restore failPoint.blockTimeMS in isMaster-timeout.json

This is a follow-up ticket for the CSHARP-2964. During the ticket implementation, I noticed that sometimes, the socket timeout exception is triggered after exceding the time that is mentioned in ReadTimeout. The gap is relatively small.
The case which I noticed: ReadTimeout: 1.25seconds, but the timeout exception has been thrown only after 1.5 seconds.
This situation led to the failed tests which used `Failpoint.blockTimeMS`.
The used workaround (when we increased blockTimeMS from 1000 to 2000ms) doesn't contradict to the test idea, but we need to investigate the underlying reasons for this behavior and make the full sync of these tests

Example of changed json test (the original json value is 1000): https://github.com/mongodb/mongo-csharp-driver/blob/master/tests/MongoDB.Driver.Tests/Specifications/server-discovery-and-monitoring/tests/integration/isMaster-timeout.json#L24