[frontend] Fix cannot add TTP directly from matrix (#6112)

[SarahBocognano]

Related issues

• Cannot add TTP directly from matrix #6112

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.68%. Comparing base (2710f7b) to head (5a5c876).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6272   +/-   ##
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  Coverage   66.68%   66.68%           
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  Files         541      541           
  Lines       64420    64420           
  Branches     5257     5257           
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  Hits        42957    42957           
  Misses      21463    21463           

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[lndrtrbn]

The initial issue is fix.
Just, is it normal that we can add multiple times the same relation between an Intrusion and a Technique? That's not directly related to the fix but now that the Add button works we face this scenario

@SarahBocognano It actually doesn't add multiple times the same relation, but yes maybe we can "disable" the add button if the relation already exist

[SarahBocognano]

Update: After a call with @nino-filigran , we will keep the "Add" button. Eveything is okay for product side, we can merge this issue like that