[SPARK-54555][PYTHON][TESTS][FOLLOW-UP] Skip pyspark-pandas doctest

### What changes were proposed in this pull request?

Skip doctest to restore pyspark-pandas CI, while docs are being updated for arrow by default

### Why are the changes needed?

Restore the CI

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

CI

### Was this patch authored or co-authored using generative AI tooling?

No

Closes #53299 from asl3/skip-pyspark-pandas.

Authored-by: Amanda Liu <[email protected]>
Signed-off-by: Ruifeng Zheng <[email protected]>

Author: asl3

python/pyspark/pandas/base.py

@@ -1367,15 +1367,15 @@ def value_counts(
                     ('falcon', 'length')],
                    )
 
-        >>> s.index.value_counts().sort_index()
+        >>> s.index.value_counts().sort_index() # doctest: +SKIP
         (cow, length)       1
         (cow, weight)       2
         (falcon, length)    2
         (falcon, weight)    1
         (lama, weight)      3
         Name: count, dtype: int64
 
-        >>> s.index.value_counts(normalize=True).sort_index()
+        >>> s.index.value_counts(normalize=True).sort_index() # doctest: +SKIP
         (cow, length)       0.111111
         (cow, weight)       0.222222
         (falcon, length)    0.222222