Squiz/ObjectInstantiation: remove keyword context test

[biinari]

Originally, this test was added in
squizlabs/PHP_CodeSniffer#836
as part of testing for allowing keywords to be used in other contexts (like
function names). This has been superseded in squizlabs/PHP_CodeSniffer#3484 to cover keywords used in different contexts in the core Tokenizer tests.

Live coding scenarios would not trigger this sniff as it only looks for
context before the 'new' keyword.

Description

Remove an unneeded test from Squiz/Objects/ObjectInstantiation that is no longer needed.

The original check for new keyword used in other contexts is covered elsewhere in the core tokenizer tests.

It is not needed as a parse error test for live coding either, as this sniff only looks for context before rather than after the new keyword.

Suggested changelog entry

N/A

Related issues/external references

See #543 for discussion. Related to #143.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
  • This change is only breaking for integrators, not for external standards or end-users.
• Documentation improvement

PR checklist

• I have checked there is no other PR open for the same change.
• I have read the Contribution Guidelines.
• I grant the project the right to include and distribute the code under the BSD-3-Clause license (and I have the right to grant these rights).
• I have added tests to cover my changes.
• I have verified that the code complies with the projects coding standards.
• [Required for new sniffs] I have added XML documentation for the sniff.

[jrfnl]

LGTM. Thanks @biinari!