Fix typos from the IntelliJ "Typos" inspection.

This closes #5242

This closes #5237

[FLINK-8203] [FLINK-7681] [table] Make schema definition of DataStream/DataSet to Table conversion more flexible

This closes #5132.

This closes #5065.

This closes #5218

Previously, NettyBufferPool only wrapped PooledByteBufAllocator but then, any
allocated buffer's alloc() method was returning the wrapped
PooledByteBufAllocator which allowed heap buffers again. By extending the
PooledByteBufAllocator, we prevent this loop hole.

This also fixes the invariant that a copy of a buffer should have the same
allocator.

This closes #4594.

[FLINK-7499][io] also let AsynchronousBufferFileWriter#writeBlock() recycle the buffer in case of failures

This fixes a double-recycle in SpillableSubpartitionView and also makes sure
that even if adding the (asynchronous) write operation fails, the buffer is
properly freed in code that did not perform this cleanup. It avoids code
duplication of this cleanup and it is also more consistent to take over
responsibility of the given buffer even if an exception is thrown.

[FLINK-7499][io] complete the idiom of ResultSubpartition#add() taking over ownership of the buffer

The buffer will now always be released once and at the right time and the caller
must not worry about the buffer release if a called function threw an exception.

This closes #4581.

- removes one level of (unneeded) abstraction for clarity

This closes #4528.

This closes #5068.

This closes #5212.

* remove unneeded semi-colons
* add `()` to `print` method
    * typically, methods with some side-effects are invoked with `()`
* fix a few misc issues

This closes #5221.

This closes #5222.

This closes #5169.

[FLINK-8326] CheckpointCoordinatorTest#testRestoreLatestCheckpointedStateScaleOut() didn't use the correct parameter to trigger test function

This closes #5141

The YarnClusterClientV2 is no longer needed since we have removed FlinkYarnCLI.

The FlinkYarnCLI is not needed and is, thus, being removed.

This closes #5217.

It is no longer needed to wait for the registration of task managers and
to not use slot sharing when submitting jobs to the Flip-6 MiniCluster.
Therefore, we can remove these work arounds from the
Flip6LocalStreamEnvironment.

Adapt comment in RestClusterClient

This closes #5101.

This closes #5142

This closes #5206

This closes #5203

This closes #5199

Now that Flink only supports builds for Scala 2.11+ we can
unconditionally enable the Kafka 0.11 connector.

This closes #5195

Update 2.7.3 to 2.7.5 and 2.8.0 to 2.8.3

This closes #5137

This is an incremental upgrade to the Scala security release 2.11.12.

This closes #5136

Double.MIN_VALUE != min(double)

This closes #5126

com.datastax.driver.core.NettyUtil expects netty to be present either at its
original package or relocated to com.datastax.shaded.netty. By relocating it
to this package we make sure the driver follows its designated path.

This closes #5183.

This closes #5148.

Since Java 8 Metaspace has replaced PermGen

This closes #5158.

This closes #4612.

This closes #5135.