Update PASSWORD_QUALITY_COMPLEX & setPasswordHistoryLength javadocs

* removed the defaults mentioned in PASSWORD_QUALITY_COMPLEX. now it
  refers the reader to setPasswordMinimumXXX docs, where they can find
  information about the default values.
* removed reference to password quality constraints from
  setPasswordMinimumLength docs since it wasn't true and doesn't make
  sense.

Test: compiles
Bug: 138922259
Change-Id: I0b31273846cfb3546d99bd27b1b0174de3d7425a