Bug: When a service account is linked to multiple flow triggers, only the first flow is triggered

Summary

When one service account is attached to two (or more) Flow Triggers in a project, only one flow is actually triggered.

Steps to reproduce

1. Create a service account with api and ai_mode permissions
2. Add the service account as a member of a project with Developer role
3. In the project, create two flow triggers, both using the created service account user. Set the trigger type as @mention
4. In an Issue or MR, @mention the service user

Example Project

What is the current bug behavior?

1. Only the first Flow Trigger is executed

What is the expected correct behavior?

Unclear. Possibilities include:

1. Trigger all associated flows
2. Only allow 1-to-1 association of Service Account to Flow Trigger

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

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`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

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(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)