Core: clarify index removal log message
Core: Let the disk threshold decider take into account shards moving away from a node in order to determine if a shard can remain.

By taking this into account we can prevent that we move too many shards away than is necessary.

Closes #8538
Closes #8659
Core: separately log file deletions

Today, you can turn on lucene.iw TRACE logging, but that produces tons
of output.  This changes breaks out separate lucene.iw.ifd and
index.store.deletes logger components (TRACE), disabled by default, to
see what part of Elasticsearch is deleting index files.

Closed #8662

Closed #8603
[TEST] Stabelize FunctionScoreBWC tests - allocation should be disabled during upgrade
[TEST] Add additional logging to memoryCircuitBreaker test
Updated docs to use v1.4.1 as current
Versions: Add 1.4.2/1.3.7 constants
[TEST] Wait for green before testing IW settings
[TEST] split base settings in ClusterDiscoveryConfiguration between node and transport client

The default settings that are currently applied to the transport client are about discovery and gateway, modules that are not even loaded on the transport client. We can now remove the local gateway as it's not the default one anyway. Also, make sure that the discovery setting is only applied to the node, as it is not relevant for transport client.

Closes #8653
[TEST] Extend unicast ports generation to support more concurrent clusters

Make it possible to run multiple tests with unicast configuration, by assigning ports based on their test scope.
Every jvm still gets its own port range based on the jvm id, but we now make sure that the different jvms ranges never overlap. The global cluster gets a reserved port range, while SUITE and TEST scopes are treated equally, just assuming that they never run concurrently on the same jvm, thus ports can be safely reused.

Closes #8634
[TEST] make sure rest tests info is printed for any @Rest annotated test

We introduced the @Rest annotation a while ago for REST tests (see #7795), we have then to make sure that relevant info to reproduce failures gets printed out for any test that is marked with such annotation, not only for ElasticsearchRestTests

Closes #8680
[TEST] remove duplicated tests.slow from randomized testing maven plugin conf
Test: UpdateTests.stressUpdateDeleteConcurrency shouldn't turn off threaded operations

This may result in all network threads being busy for too long.
[HEALTH] Don't mark health as timed out if desired state is reached

Today we mark cluster health requests as timed out if the request has already
timed out. Yet, and implementation detail of the health request is that we are
waiting for events which can take quite some time if the machine is busy. If
we have already reached a valid state while waiting for events to be processed
we shouldn't mark the clusterstate as timed-out. This will help tests that
wait for green state with lots of nodes and shards to not fail the cluster health
calls.
[CLIENT] Only fetch the node info during node sampling

Today we are fetching a lot of information that is unneeded
for the sampling phase. We only really need the DiscoveryNode
to ensure the node is still there.
This commit clears all flags to be false on the NodeInfo call.
Test: predefine sort fields in mapping, otherwise during the test the field may not be found if it were to be introduced dynamically at index time.
[Docs] Fix missing new line
[Docs] Fix missing comma in mapping
[Docs] fix consistency between examples
[TEST] Reduce possible number of indices in the test - 10 indices can create tons of shards