Tweak reindex cancel logic and add many debug logs (#25256)

I'm still trying to hunt down rare failures in the cancelation tests
for reindex and friends. Here is the latest:
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+5.x+multijob-unix-compatibility/os=ubuntu/876/console

It doesn't show much, other than that one of the tasks didn't kill
itself when asked to cancel.

So I'm going a bit crazy with debug logging so that the next time this
comes up I can trace exactly what happened.

Additionally, this tweaks the logic around how rethrottles were
performed around cancel. Previously we set the `requestsPerSecond`
to `0` when we cancelled the task. That was the "old way" to set them
to inifity which was the intent. This switches that from `0` to
`Float.MAX_VALUE` which is the "new way" to set the `requestsPerSecond`
to infinity. I don't know that this is much better, but it feels better.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/framework/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollActionTestCase.java b/test/framework/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollActionTestCase.java
index b4e01b18a5..079c784342 100644
--- a/test/framework/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollActionTestCase.java
+++ b/test/framework/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollActionTestCase.java
@@ -37,7 +37,7 @@ public abstract class AbstractAsyncBulkByScrollActionTestCase<
     @Before
     public void setupForTest() {
         threadPool = new TestThreadPool(getTestName());
-        task = new WorkingBulkByScrollTask(1, "test", "test", "test", TaskId.EMPTY_TASK_ID, null, 0);
+        task = new WorkingBulkByScrollTask(1, "test", "test", "test", TaskId.EMPTY_TASK_ID, null, Float.MAX_VALUE);
     }
 
     @After