[SPARK-14704][CORE] create accumulators in TaskMetrics

[cloud-fan]

What changes were proposed in this pull request?

Before this PR, we create accumulators at driver side(and register them) and send them to executor side, then we create TaskMetrics with these accumulators at executor side.
After this PR, we will create TaskMetrics at driver side and send it to executor side, so that we can create accumulators inside TaskMetrics directly, which is cleaner.

How was this patch tested?

existing tests.

[cloud-fan]

cc @rxin @JoshRosen @andrewor14

[SparkQA]

Test build #56065 has finished for PR 12472 at commit 9eb2a87.

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

[cloud-fan]

ready for review :)

[SparkQA]

Test build #56193 has finished for PR 12472 at commit 6226058.

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

[rxin]

while you are at this, can you document this is only used for testing?

[rxin]

We should be able to remove almost all the methods on InternalAccumulators.scala, shouldn't we? All that includes create, createAll, createShuffleReadAccums, ...

[SparkQA]

Test build #56204 has finished for PR 12472 at commit b82e90e.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #56207 has finished for PR 12472 at commit bfa39ff.

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

[rxin]

looks pretty good now

[SparkQA]

Test build #56211 has finished for PR 12472 at commit eff1790.

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

[SparkQA]

Test build #56227 has finished for PR 12472 at commit 7f00198.

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

[cloud-fan]

retest this please

[SparkQA]

Test build #56300 has finished for PR 12472 at commit 7f00198.

• This patch fails build dependency tests.
• This patch does not merge cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #56306 has finished for PR 12472 at commit b80f3d0.

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

[SparkQA]

Test build #56310 has finished for PR 12472 at commit 471c1e3.

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

[rxin]

Thanks - merging in master.