[SPARK-37407][FOLLOW-UP][PYTHON][ML] Add not None assertions for active context and its _jvm

[zero323]

What changes were proposed in this pull request?

This PR add is not None assertions for Optional _active_spark_context and _jvm

Why are the changes needed?

To address failures in CI:

python/pyspark/ml/functions.py:69: error: Item "None" of "Optional[SparkContext]" has no attribute "_jvm"  [union-attr]
python/pyspark/ml/functions.py:69: error: Item "None" of "Optional[Any]" has no attribute "org"  [union-attr]
python/pyspark/ml/functions.py:104: error: Item "None" of "Optional[SparkContext]" has no attribute "_jvm"  [union-attr]
python/pyspark/ml/functions.py:104: error: Item "None" of "Optional[Any]" has no attribute "org"  [union-attr]

caused by divergence between #34678 and changes introduced by #34892

Does this PR introduce any user-facing change?

No.

How was this patch tested?

dev/lint-python

[zero323]

I am going to merge to it to address current failure on master.

[zero323]

Merged into master.