bisector: Don't checkout submodules

The bisector only looks at the top-level git log.

Bug: b/401921575
Change-Id: I07b0178ba743857b40fa95576442d133d70ae28a
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/274533
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Dave Roth <davidroth@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/recipes/bisector.py b/recipes/bisector.py
index f91d195..b1b5860 100644
--- a/recipes/bisector.py
+++ b/recipes/bisector.py
@@ -178,6 +178,7 @@
                             CheckoutOptions(
                                 remote=remote.url,
                                 branch=remote.branch,
+                                initialize_submodules=False,
                             ),
                             root=root / 'checkout',
                         )