[SPARK-37244][PYTHON][FOLLOWUP] Adjust `pyspark.rdd` doctest
[SPARK-37244][PYTHON][FOLLOWUP] Adjust `pyspark.rdd` doctest

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

This PR is a follow-up of https://github.com/apache/spark/pull/34526 to adjust one `pyspark.rdd` doctest additionally.

```python
- >>> b''.join(result).decode('utf-8')
+ >>> ''.join([r.decode('utf-8') if isinstance(r, bytes) else r for r in result])
```
### Why are the changes needed?

**Python 3.8/3.9**
```python
Using Python version 3.8.12 (default, Nov  8 2021 17:15:19)
Spark context Web UI available at http://localhost:4040
Spark context available as 'sc' (master = local[*], app id = local-1636432954207).
SparkSession available as 'spark'.
>>> from tempfile import NamedTemporaryFile
>>> tempFile3 = NamedTemporaryFile(delete=True)
>>> tempFile3.close()
>>> codec = "org.apache.hadoop.io.compress.GzipCodec"
>>> sc.parallelize(['foo', 'bar']).saveAsTextFile(tempFile3.name, codec)
>>> from fileinput import input, hook_compressed
>>> from glob import glob
>>> result = sorted(input(glob(tempFile3.name + "/part*.gz"), openhook=hook_compressed))
>>> result
[b'bar\n', b'foo\n']
```

**Python 3.10**
```python
Using Python version 3.10.0 (default, Oct 29 2021 14:35:18)
Spark context Web UI available at http://localhost:4040
Spark context available as 'sc' (master = local[*], app id = local-1636433378727).
SparkSession available as 'spark'.
>>> from tempfile import NamedTemporaryFile
>>> tempFile3 = NamedTemporaryFile(delete=True)
>>> tempFile3.close()
>>> codec = "org.apache.hadoop.io.compress.GzipCodec"
>>> sc.parallelize(['foo', 'bar']).saveAsTextFile(tempFile3.name, codec)
>>> from fileinput import input, hook_compressed
>>> from glob import glob
>>> result = sorted(input(glob(tempFile3.name + "/part*.gz"), openhook=hook_compressed))
>>> result
['bar\n', 'foo\n']
```

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

No.

### How was this patch tested?

```
$ python/run-tests --testnames pyspark.rdd
```

Closes #34529 from dongjoon-hyun/SPARK-37244-2.

Authored-by: Dongjoon Hyun <6ff48b33cbb828151035af58a92f18a39f1d1036@apache.org>
Signed-off-by: Hyukjin Kwon <2680965ad5aae29275c8fb10150cb10f5554e78b@apache.org>

JoshRosen/spark,HyukjinKwon/spark,WeichenXu123/spark,zero323/spark,JoshRosen/spark,JoshRosen/spark,vinodkc/spark,cloud-fan/spark,apache/spark,srowen/spark,HyukjinKwon/spark,dongjoon-hyun/spark,hvanhovell/spark,zero323/spark,witgo/spark,HyukjinKwon/spark,zzcclp/spark,vinodkc/spark,ueshin/apache-spark,gengliangwang/spark,holdenk/spark,WeichenXu123/spark,rednaxelafx/apache-spark,JoshRosen/spark,hvanhovell/spark,hvanhovell/spark,xuanyuanking/spark,dongjoon-hyun/spark,gengliangwang/spark,ueshin/apache-spark,srowen/spark,apache/spark,wangyum/spark,xuanyuanking/spark,holdenk/spark,zero323/spark,srowen/spark,dongjoon-hyun/spark,dongjoon-hyun/spark,holdenk/spark,HyukjinKwon/spark,gengliangwang/spark,wangyum/spark,apache/spark,wangyum/spark,zero323/spark,hvanhovell/spark,nchammas/spark,hvanhovell/spark,vinodkc/spark,vinodkc/spark,vinodkc/spark,ueshin/apache-spark,shaneknapp/spark,cloud-fan/spark,shaneknapp/spark,srowen/spark,xuanyuanking/spark,JoshRosen/spark,witgo/spark,cloud-fan/spark,apache/spark,zzcclp/spark,wangyum/spark,wangyum/spark,zzcclp/spark,srowen/spark,HyukjinKwon/spark,cloud-fan/spark,HyukjinKwon/spark,shaneknapp/spark,mahak/spark,zero323/spark,rednaxelafx/apache-spark,zero323/spark,rednaxelafx/apache-spark,mahak/spark,xuanyuanking/spark,gengliangwang/spark,cloud-fan/spark,wangyum/spark,WeichenXu123/spark,mahak/spark,ueshin/apache-spark,apache/spark,mahak/spark,witgo/spark,holdenk/spark,mahak/spark,zzcclp/spark,nchammas/spark,WeichenXu123/spark,witgo/spark,hvanhovell/spark,wangyum/spark,ueshin/apache-spark,WeichenXu123/spark,vinodkc/spark,zero323/spark,shaneknapp/spark,mahak/spark,rednaxelafx/apache-spark,gengliangwang/spark,hvanhovell/spark,mahak/spark,WeichenXu123/spark,nchammas/spark,dongjoon-hyun/spark,WeichenXu123/spark,apache/spark,dongjoon-hyun/spark,zzcclp/spark,shaneknapp/spark,nchammas/spark,HyukjinKwon/spark,zzcclp/spark,rednaxelafx/apache-spark,rednaxelafx/apache-spark,vinodkc/spark,xuanyuanking/spark,nchammas/spark,cloud-fan/spark,ueshin/apache-spark,nchammas/spark,ueshin/apache-spark,srowen/spark,witgo/spark,shaneknapp/spark,zzcclp/spark,shaneknapp/spark,holdenk/spark,gengliangwang/spark,witgo/spark,cloud-fan/spark,dongjoon-hyun/spark,JoshRosen/spark,nchammas/spark,holdenk/spark,srowen/spark,JoshRosen/spark,holdenk/spark,rednaxelafx/apache-spark,xuanyuanking/spark,witgo/spark,gengliangwang/spark,xuanyuanking/spark,apache/spark