Fixing a couple of issues with DenseFeatures
Fixing a couple of issues with DenseFeatures

1. Fixing variable_scope to not pass in partition_info argument if its in V2 mode. This ensures compatibility with V2 initializers
2. Adding a tracking_name argument to add_variable which allows for passing in a different name for tracking purposes without affecting the variable name.

PiperOrigin-RevId: 264658202

tensorflow/estimator,tensorflow/estimator