regression: unable to pass BUILDKITE_ADDITIONAL_HOOKS_PATHS

[aeijdenberg-canva]

Describe the bug

BUILDKITE_ADDITIONAL_HOOKS_PATHS seems to have no effect anymore.

Steps To Reproduce

We set BUILDKITE_ADDITIONAL_HOOKS_PATHS to a set of script that we expect to run.

We pass this via a container env variable.

Expected behavior

Them to run like they did in 3.115.3.

Actual behaviour

They did not run.

Stack parameters (please complete the following information)

• Works in 3.115.3
• Does not work in 3.127.1

Affiliation (optional)

Canva

Additional context

I suspect this PR changed the behaviour:
#3944