Fix visual bugs on concentrator pages

[audserraCGI]

Description

What's new?

• Bug: Access to the last region in the concentrator creation page #377

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Tests
• Other

[codecov]

Codecov Report

Merging #394 (b951093) into main (0c6efa6) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #394      +/-   ##
==========================================
+ Coverage   50.27%   50.29%   +0.01%     
==========================================
  Files         101      101              
  Lines        2896     2895       -1     
==========================================
  Hits         1456     1456              
+ Misses       1440     1439       -1     

Impacted Files	Coverage Δ
.../LoRaWAN/Concentrator/ConcentratorDetailPage.razor	0.00% <ø> (ø)
.../LoRaWAN/Concentrator/CreateConcentratorPage.razor	0.00% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0c6efa6...b951093. Read the comment docs.