Pass maximum over all NLS's in staggered coupling

Current implementation is taking last staggered process number of iterations to pass it to time stepping scheme. Much better is to take the maximum of all processes and the global staggered loop, so T, H, and C have some iterations and there are S global iterations, then we pass max(T, H, C, S) to the time stepper.

1. Tests covering your feature were added? existing tests
2. Any new feature or behaviour change was documented?

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