[SPARK-11073] [core] [yarn] Remove akka dependency in secret key generation.

[vanzin]

Use standard JDK APIs for that (with a little help from Guava). Most of the
changes here are in test code, since there were no tests specific to that
part of the code.

[rxin]

cc @tgravescs

[SparkQA]

Test build #44270 has finished for PR 9257 at commit 98761dd.

• This patch fails PySpark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class DefaultSource extends HadoopFsRelationProvider with DataSourceRegister\n * class TextOutputWriter(path: String, dataSchema: StructType, context: TaskAttemptContext)\n

[vanzin]

retest this please

[SparkQA]

Test build #44283 has finished for PR 9257 at commit 98761dd.

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

[SparkQA]

Test build #44304 has finished for PR 9257 at commit c6c9823.

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

[vanzin]

not sure what failed. retest this please

[SparkQA]

Test build #44303 has finished for PR 9257 at commit 35002a9.

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

[SparkQA]

Test build #44305 has finished for PR 9257 at commit c6c9823.

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

[tgravescs]

any reason not to leave the debug messages?

[vanzin]

They didn't feel particularly useful.

[tgravescs]

I'd prefer to see this one left. Otherwise there is no easy way to see what its doing for the secret. In general I'm against removing debug stuff unless its really really noisy. This should only be printed once and can be useful debugging user settings or issues with secrets.

[vanzin]

ok

[SparkQA]

Test build #44512 has finished for PR 9257 at commit c6cde97.

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

[tgravescs]

+1 pending Jenkins.

[SparkQA]

Test build #44528 has finished for PR 9257 at commit b4a29bf.

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

[SparkQA]

Test build #44771 has finished for PR 9257 at commit 0878148.

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

[vanzin]

Merging this.