perf: make request to /contactsmenu/teams only when contacts menu is opened

[cristianscheid]

• Resolves: #

Summary

• a GET contactsmenu/teams request was being made on every page load
• this happened because the endpoint was being called inside onMounted, and since the contacts menu is on the header of the page, every page load triggered it
• moved the GET contactsmenu/teams request inside the onOpened function, so it's only triggered when the contacts menu is actually opened
• with this fix, the request is only made when clicking on the contacts menu for the first time, subsequent openings of the menu do not trigger it again, only if the page is reloaded

for context, contacts menu:

changes look good from my tests, functionality keeps working as expected

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[cristianscheid]

/backport to stable35

[Antreesy]

Should be good now, thanks for addressing)