Update MBM tutorial with modern, non-deprecated functionality and acc…

…urate description of defaults (#2466)

Summary:
Pull Request resolved: #2466

* Use log acquisition functions
* Remove references to deprecated fixed-noise acquisition functions (now absorbed into more general acqfs)
* Correct inaccuracies in description of MBM defaults
* Removed unused imports

Reviewed By: mgarrard

Differential Revision: D57443923

fbshipit-source-id: c56ec0bc79ccdc24b343c773b89e6dbb54a160e0