[SPARK-3225]Typo in script

use_conf_dir => user_conf_dir in load-spark-env.sh.

Author: WangTao <barneystinson@aliyun.com>

Closes #1926 from WangTaoTheTonic/TypoInScript and squashes the following commits:

0c104ad [WangTao] Typo in script
[SPARK-2964] [SQL] Remove duplicated code from spark-sql and start-thriftserver.sh

Author: Cheng Lian <lian.cs.zju@gmail.com>
Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #1886 from sarutak/SPARK-2964 and squashes the following commits:

8ef8751 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-2964
26e7c95 [Kousuke Saruta] Revert "Shorten timeout to more reasonable value"
ffb68fa [Kousuke Saruta] Modified spark-sql and start-thriftserver.sh to use bin/utils.sh
8c6f658 [Kousuke Saruta] Merge branch 'spark-3026' of https://github.com/liancheng/spark into SPARK-2964
81b43a8 [Cheng Lian] Shorten timeout to more reasonable value
a89e66d [Cheng Lian] Fixed command line options quotation in scripts
9c894d3 [Cheng Lian] Fixed bin/spark-sql -S option typo
be4736b [Cheng Lian] Report better error message when running JDBC/CLI without hive-thriftserver profile enabled
[Docs] Run tests like in contributing guide

The Contributing to Spark guide [recommends](https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark#ContributingtoSpark-AutomatedTesting) running tests by calling `./dev/run-tests`. The README should, too.

`./sbt/sbt test` does not cover Python tests or style tests.

Author: nchammas <nicholas.chammas@gmail.com>

Closes #2149 from nchammas/patch-2 and squashes the following commits:

2b3b132 [nchammas] [Docs] Run tests like in contributing guide