fix: select cidr field only in non-TRE env

[SanketD92]

Issue #, if available:
N/A

Description of changes:
Compute UI errors for CIDR only in non-TRE environments.

Checklist:

• Have you successfully deployed to an AWS account with your changes?
• Have you successfully tested with your changes locally?

AS review ticket id:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Merging #941 (8ad3c51) into develop (dd2ccfd) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #941   +/-   ##
========================================
  Coverage    51.44%   51.44%           
========================================
  Files          295      295           
  Lines        16784    16784           
  Branches      2596     2596           
========================================
  Hits          8634     8634           
  Misses        7163     7163           
  Partials       987      987           

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