Allow Instance executor to use a common build directory
What does this MR do?
Adds a new config option UseCommonBuildDir to control the generated build directory.
Why was this MR needed?
The Instance executor by default is setup for its build directory to be shared by multiple concurrent jobs executing.
It does so using a unique path per project: builds_dir/runner-short-id/concurrent-id/group-name/project-name.
However, this default doesn't always make sense when VM Isolation is enabled or max_use_count is 1.
This MR adds a new Instance config option UseCommonBuildDir to enable the use of a common build directory in these circumstances.
What's the best way to test this MR?
What are the relevant issue numbers?
Edited by Arran Walker