[GitLab] Issue creation modal takes too long to load

### Environment SaaS (https://sentry.io/) ### Steps to Reproduce 1. Have a GitLab org with many projects 2. Integrate it into Sentry through the GitLab integration 3. Link Sentry projects to GitLab repositories 4. Pick an issue in Sentry and try to create/link it to a GitLab issue ### Expected Result The modal loads immediately. ### Actual Result The modal takes 19s (or more) to load. - The customer has checked the logs for Chrome and the DNS AdBlock - neither are slowing down or denying access to any requests. - In incognito mode with no browser extensions it is exactly the same. - The network is 1GBps, with 6ms latency, tested on their machine using fast.com - No VPN - Nothing in any firewall rules that could be causing the response time from Sentry's end to be slow Org and video repro in [the shadow ticket](https://getsentry.atlassian.net/browse/FEEDBACK-2402?atlOrigin=eyJpIjoiZWFkMzliY2EzOThhNGMyMGE3NGUyZTI3NTg5MzFmYjYiLCJwIjoiaiJ9) as I couldn't reproduce the issue on my end when trying to create a GitLab issue in the customer's org. ### Product Area Settings - Integrations ### Link _No response_ ### DSN _No response_ ### Version _No response_