With Bzlmod enabled, --override_repository won't work unless the repo is already declared in MODULE.bazel or WORKSPACE.bzlmod.

Fixes https://buildkite.com/bazel/bazel-bazel/builds/24789#018a8395-d29c-4988-ae12-5b9c80efee33

RELNOTES: None
PiperOrigin-RevId: 564353458
Change-Id: I1858d54a9c0b1b5ed6634a2c21a44094f81233f6