Remove constraint indexes if data is not unique.

When failing to create a unique index for a uniqueness constraint, the
index should be dropped immediately.

Fixes mistakes made in ConstraintIndexCreator in
e1e3b987343a0df878d6beda76a1b09c6330f7f1 where the index was no longer
removed if creation failed, and in its tests in
718635a384820e98853609499116e17482a99b85 where the test did no longer
assert this behaviour.

Fixes #1492.
Update the Enterprise CacheProvider configuration point to the renamed HighPerformanceCacheProvider.
Merge pull request #1495 from thobe/2.0-remove-failed-constraint-index

Remove constraint indexes if data is not unique.
Cleanup of haversin example. Added note on syntax change re optional rels.
Unused imports.
Updated CHANGES.txt with the GCR to HPC rename.
Merge pull request #1496 from jakewins/fix-slipup-in-renaming-gcr-to-hpc

Fix slipup in renaming gcr to hpc
Include browser in the regular build.
Revert "Include browser in the regular build."

This reverts commit f8e12775eefc4d45c164c8f0cb462efc532e5dac.
removed undesirable config properties from built-in default file
Useful method for checking if any of the causes in a Throwable is of a particular class
Refactoring of OPTIONAL MATCH
Merge pull request #1500 from akollegger/desktop-recommended-props

[Desktop] removed undesirable config properties from built-in default file
Add MERGE for patterns with more than single nodes
Remove the identifier following ON CREATE / ON MATCH

Currently this is not required in the language
Merge pull request #1501 from systay/merge-concurrency

Add MERGE for patterns with more than single nodes
Print diagnostics inside the Windows build [to be reverted]
Revert "Print diagnostics inside the Windows build [to be reverted]"

This reverts commit f7c09f6cc7d111b9b97d0ea51eac851ce5a1307a.
Remove rethrowing of exceptions at shutdown
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