apply setParameter for maxSyncSourceLagSecs to slave 2 only in maxSyncSourceLagSecs.js

We can stabilize the test by selectively apply change maxSyncSourceLagSecs on slave 2 only instead of both slaves 1 and 2.

---- update —
maxSyncSourceLagSecs.js changes how the secondaries sync from one another. It is appropriate to use the fail point introduced in SERVER-27231 to stabilize the test.