Allow large stack frame in proposer_boost_re_org_test

Rust 1.94.0 raised `clippy::large_stack_frames` against this function
(548365 bytes vs. 512000 default threshold), failing pre-push lint.
Match the per-function `#[allow]` pattern used elsewhere in the
codebase (store_tests.rs, basic_sim.rs, etc.).

beacon_node/http_api/tests/interactive_tests.rs

@@ -385,6 +385,7 @@ pub async fn proposer_boost_re_org_weight_misprediction() {
 /// - `num_empty_votes`: percentage of comm of attestations for the parent block
 /// - `num_head_votes`: number of attestations for the head block
 /// - `should_re_org`: whether the proposer should build on the parent rather than the head
+#[allow(clippy::large_stack_frames)]
 pub async fn proposer_boost_re_org_test(
     ReOrgTest {
         head_slot,