French translation fixes

[feloy]

Revert some hacks introduced in #3770

• Revert the usage of hidden hidden element as a workaround for tooltip message logic
• Add a locale-config parameter to the dashboard binary

[codecov]

Codecov Report

Merging #3812 into master will decrease coverage by 0.03%.
The diff coverage is 0%.

@@            Coverage Diff            @@
##           master   #3812      +/-   ##
=========================================
- Coverage   47.14%   47.1%   -0.04%     
=========================================
  Files         171     171              
  Lines        7971    7971              
  Branches       62      62              
=========================================
- Hits         3758    3755       -3     
- Misses       3972    3976       +4     
+ Partials      241     240       -1

Impacted Files	Coverage Δ
src/app/backend/handler/localehandler.go	62.71% <0%> (ø)	⬆️
src/app/backend/sync/secret.go	70.29% <0%> (-2.98%)	⬇️

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[maciaszczykm]

/lgtm
/approve

[maciaszczykm]

/hold for @floreks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: feloy, maciaszczykm

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[maciaszczykm]

Ups, /hold didn't work...

[floreks]

It's fine. We did not have support for i18n testing on prod before. LGTM. Thanks!