removing netstandard1.x branching

[eddynaka]

Fix Issue #1767

Changes

• removing branching #if netstandard1_x
• removing inversed branching #if !netstandard1_x

Checklist

• I ran Unit Tests locally.
• CHANGELOG.md updated with one line description of the fix, and a link to the original issue if available.

For significant contributions please make sure you have completed the following items:

• Design discussion issue #
• Changes in public surface reviewed

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