fix: correct datatest to data-testid attribute

[MuraariK13052008]

What this fixes

The Edit Campaign button used a non-standard datatest= attribute instead of the standard data-testid= used consistently across the rest of the codebase. The Cypress tests also used [datatest="editbutton"] selectors to match, so the tests passed — but both sides were wrong together.

Root cause

Line 18 of ViewCampaign.vue sets datatest="editbutton" (a made-up attribute). The Cypress tests in campaign.cy.js lines 42 and 55 query [datatest="editbutton"] to match it. Since both sides shared the same non-standard attribute, tests passed. Every other testable element in the codebase uses data-testid=.

Fix

• Changed datatest= → data-testid= in ViewCampaign.vue line 18
• Updated both Cypress selectors in campaign.cy.js lines 42 and 55 to [data-testid="editbutton"]

Files changed

• frontend/src/components/Campaign/ViewCampaign.vue
• frontend/cypress/e2e/campaign.cy.js

How to verify

1. Run Cypress tests — all existing edit button tests should still pass
2. Inspect the Edit Campaign button in browser devtools — confirm it has data-testid="editbutton" not datatest="editbutton"

Relates to: T415578