Remove incompatible_depset_is_not_iterable from bazelrc

This flag is default-on now, and is being removed in the next version of Bazel. Thus, this inclusion in bazelrc was breaking buildkite against Bazel@HEAD.

PiperOrigin-RevId: 283787955
diff --git a/.bazelrc b/.bazelrc
index 6005eaa..01026c9 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -10,6 +10,3 @@
 
 # Enable the "Managed Directories" feature
 common --experimental_allow_incremental_repository_updates
-
-# Opt-in to upcoming breaking change
-build --incompatible_depset_is_not_iterable