fix: use encoded address for refund_address in events

[dandanlen]

Pull Request

Closes: PRO-1553

Checklist

Please conduct a thorough self-review before opening the PR.

• [ ] I am confident that the code works. (Waiting for tests to pass)
• [x] I have written sufficient tests. (updated existing tests)
• [x] I have written and tested required migrations. (none require)
• [x] I have updated documentation where appropriate. (nothing required afaict)

Summary

Please include a succinct description of the purpose and content of the PR. What problem does it solve, and how? Link issues, discussions, other PRs, and anything else that will help the reviewer.

See Linear description.

Changes are potentially engine-breaking (event update) which is why it would be good to include this in 1.5.1

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 60.71429% with 11 lines in your changes missing coverage. Please review.

Project coverage is 71%. Comparing base (667a10a) to head (8d38285).

Files	Patch %	Lines
api/lib/src/lib.rs	0%	5 Missing :warning:
state-chain/pallets/cf-ingress-egress/src/lib.rs	33%	2 Missing :warning:
...ess-egress/src/migrations/add_broker_fee_to_ccm.rs	0%	2 Missing :warning:
state-chain/pallets/cf-swapping/src/lib.rs	80%	1 Missing :warning:
state-chain/traits/src/lib.rs	0%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/1.5 #5135 +/- ## =========================================== Coverage 71% 71% =========================================== Files 446 446 Lines 77037 77049 +12 Branches 77037 77049 +12 =========================================== + Hits 54672 54684 +12 - Misses 19427 19431 +4 + Partials 2938 2934 -4 ```

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