Removed DefaultExecutionTopology.ensureCoLocatedVerticesInSameRegion(..) as
CoLocationConstraint is not used anymore.

FLINK-20589

Remove CoLocationConstraint from ExeuctionVertexSchedulingRequirements as it is
not used anymore.

FLINK-20589

This test verifies that the CoLocationConstraint is reset when recovering the
task. We still need to verify whether it should be replaced.

FLINK-20589

This test verifies that the CoLocationConstraints are created which is not the
case anymore.

FLINK-20589

…rtex

The CoLocation information isn't processed through the ExecutionVertex anymore
but is calculated statically by the LocalInputPreferredSlotSharingStrategy.

FLINK-20589

The CoLocationConstraints are not used anymore but replaced by
LocalInputPreferredSlotSharingStrategy.

FLINK-20589

The CoLocationConstraints is not used anymore and, therefore, can be removed
from the CoLocationGroup.

FLINK-20589

CoLocationConstraint is deleted. Its JavaDoc is copied over to
CoLocationConstraintDesc and adjusted accordingly.

FLINK-20589

The CoLocationGroup only needs to be adapted within JobVertex. Any other
locations can rely on CoLocationGroupDesc's read-only methods.

FLINK-20589

Minor cleanup to follow Intellij suggestions.

FLINK-20589

Previously, the CoLocationConstraints have been reset in this method. The
CoLocationGroup handling is not needed anymore after the reset functionality
was removed.

FLINK-20589

…face

The interface CoLocationGroupDesc was introduced wherever possible.

FLINK-20589

We need to ensure that co-located tasks are executed in the same pipeline
region. Hence, 8b1510c was reverted.

FLINK-20589

CoLocationGroupDesc.getVertices was renamed: The refactoring changed the return
type and, therefore, made the renaming necessary.

FLINK-20589

The old implementation relied on the CoLocationConstraint only being created
once. Switching to CoLocationConstraintDesc changed that behavior. Hence, we
have to switch from IdentityHashMap to HashMap.

FLINK-20589

After finalizing the refactoring of removing CoLocationConstraint and making
CoLocationGroupDesc an interface, it is now reasonable to rename the affected
classes and interfaces accordingly:
* CoLocationGroup -> CoLocationGroupImpl
* CoLocationGroupDesc -> CoLocationGroup
* CoLocationConstraintDesc -> CoLocationConstraint

FLINK-20589

FLINK-20589

Minor renamings are applied that were brought up during the review.
Additionally, missing JavaDoc was added.