The feature is called CodeIndex, and that's why I could not find it earlier.
Here's all the info required to configure it: https://docs.microsoft.com/en-us/visualstudio/ide/codeindex-command?view=vs-2015
I turned it off and I am now trying to destroy the index, but it errors out with
TF246018: The database operation exceeded the timeout limit and has
The collection is unavailable. Meaning, people can't access this code repositories, package feeds, work items etc. When using TFVC server workspaces this will take local copies of code offline, increasing the chances of merge conflicts. Any tools and service hooks will be unavailable too.
To prepare users can:
check in their changes.
make sure they have ...