[SPARK-10608][CORE] disable reduce locality as default

[liyezhang556520]

for details, pls refer to SPARK-10608

[SparkQA]

Test build #42478 has finished for PR 8765 at commit ce3eb79.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[liyezhang556520]

jenkins, retest this please

[SparkQA]

Test build #42486 has finished for PR 8765 at commit ce3eb79.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #43073 has finished for PR 8765 at commit ce3eb79.

• This patch fails PySpark unit tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[JoshRosen]

/cc @shivaram @mateiz

[zsxwing]

@liyezhang556520 could you update this PR? Thanks!

[liyezhang556520]

@zsxwing , Since the original implementation has changed a lot, let me close this PR/JIRA first, if the issue still exists, I'll reopen.