fix(test): correct cross-call event-count assumption in ownership-transfer test

[thlpkee20-wq]

Summary

test_transfer_service_ownership_genuine_transfer_emits_event fails on
current main (confirmed against a clean checkout, unrelated to any of
my other in-flight PRs on this repo). It compares
env.events().all().len() before and after transfer_service_ownership,
assuming the event log accumulates across separate top-level client
calls (set_service_metadata then transfer_service_ownership). In
this soroban-sdk version, env.events().all() is scoped to the
current invocation, so the delta assertion always fails even though the
contract correctly emits owner_chg on every genuine transfer (the
event is there — the test's own subsequent assertions on
events_after.last() already prove that).

Fix

Matched the established, working pattern used elsewhere in this file
(e.g. test_settle_emits_settled_event_with_payload): assert the event
log is non-empty and check the most recent publish's topic/payload,
instead of a before/after delta.

Test plan

• cargo fmt --all -- --check
• cargo clippy --all-targets -- -D warnings
• cargo test — 336/336 passing (was 335 passed, 1 failed before
  this fix)

This is a test-only fix, not tied to a specific GrantFox issue — it
unblocks a clean cargo test run for every other PR touching this repo.

[mikewheeleer]

thanks @thlpkee20-wq! please add a Closes #<issue> line to the PR description so it links to the issue it resolves — then we can review and merge. 🙏

[mikewheeleer]

thanks @thlpkee20-wq! please add a Closes #<issue> line to the PR description so it links to the issue it resolves — then we can review and merge. 🙏

[mikewheeleer]

thanks @thlpkee20-wq! please add a Closes #<issue> line to the PR description so it links to the issue it resolves — then we can review and merge. 🙏