UI: fix CreateIsolatedNetworkForm.vue

[weizhouapache]

Description

This PR fixes the CreateIsolatedNetworkForm.vue in main/4.20 branch.

Due to PR #8919 , the PR #9348 should be ignored in main/4.20 branch.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• build/CI
• test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

How did you try to break this feature and the system with this change?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 4.17%. Comparing base (0af8835) to head (dad8f11).

❗ There is a different number of reports uploaded between BASE (0af8835) and HEAD (dad8f11). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (0af8835)	HEAD (dad8f11)
unittests	1	0

Additional details and impacted files

@@ Coverage Diff @@## main #9359 +/- ##
============================================
- Coverage 15.53% 4.17% -11.37% 
============================================
Files 5492 371 -5121 Lines 480931 30420 -450511 Branches 61853 5390 -56463 ============================================
- Hits 74711 1269 -73442 + Misses 397959 29007 -368952 + Partials 8261 144 -8117 

Flag	Coverage Δ
uitests	4.17% <ø> (+<0.01%)	⬆️
unittests	?

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[DaanHoogland]

clgtm