[SPARK-8845] [ML] ML use of Breeze optimization: use adjustedValue instead of value

In LinearRegression and LogisticRegression, we use Breeze's optimizers (LBFGS and OWLQN). We check the State.value to see the current objective. However, Breeze's documentation makes it sound like value and adjustedValue differ for some optimizers, possibly including OWLQN: https://github.com/scalanlp/breeze/blob/26faf622862e8d7a42a401aef601347aac655f2b/math/src/main/scala/breeze/optimize/FirstOrderMinimizer.scala#L36
If that is the case, then we should use adjustedValue instead of value. This is relevant to SPARK-8538 and SPARK-8539, where we will provide the objective trace to the user.

Author: DB Tsai <dbt@netflix.com>

Closes #7245 from dbtsai/SPARK-8845 and squashes the following commits:

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