[SPARK-3128][MLLIB] Use streaming test suite for StreamingLR

Refactored tests for streaming linear regression to use existing  streaming test utilities. Summary of changes:
- Made ``mllib`` depend on tests from ``streaming``
- Rewrote prediction and convergence tests to use ``setupStreams`` and ``runStreams``
- Added new test for the accuracy of predictions generated by ``predictOnValue``

These tests should run faster, be easier to extend/maintain, and provide a reference for new tests.

@mengxr @tdas