[SPARK-13501] Remove use of Guava Stopwatch

[JoshRosen]

Our nightly doc snapshot builds are failing due to some issue involving the Guava Stopwatch constructor:

[error] /home/jenkins/workspace/spark-master-docs/spark/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala:496: constructor Stopwatch in class Stopwatch cannot be accessed in class CoarseMesosSchedulerBackend
[error]     val stopwatch = new Stopwatch()
[error]                     ^

This Stopwatch constructor was deprecated in newer versions of Guava (google/guava@fd0cbc2) and it's possible that some classpath issues affecting Unidoc could be causing this to trigger compilation failures.

In order to work around this issue, this patch removes this use of Stopwatch since we don't use it anywhere else in the Spark codebase.

[JoshRosen]

/cc @andrewor14 for review.

[andrewor14]

lgtm

[andrewor14]

This passed the mesos tests already. Merging into master.

[SparkQA]

Test build #52001 has finished for PR 11376 at commit ecc21ac.

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

[srowen]

+1 Stopwatch has been problematic for me since the two ways of making it (constructor, factory) only both exist in a few versions. So it's frequently a problem in both directions.