feat: add external expiry block to event [WEB-496]

[acdibble]

Pull Request

Closes: WEB-496

Checklist

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

• I am confident that the code works.
• I have updated documentation where appropriate.

Summary

Replaces the old expiry_block

[linear]

WEB-496 Handle new expiry logic

[codecov]

Codecov Report

Merging #4097 (c9a824d) into main (2a7e6b2) will decrease coverage by 0%.
Report is 2 commits behind head on main.
The diff coverage is 80%.

@@          Coverage Diff          @@
##            main   #4097   +/-   ##
=====================================
- Coverage     71%     71%   -0%     
=====================================
  Files        377     377           
  Lines      60015   60034   +19     
  Branches   60015   60034   +19     
=====================================
- Hits       42756   42745   -11     
- Misses     15015   15045   +30     
  Partials    2244    2244           

Files	Coverage Δ
state-chain/pallets/cf-ingress-egress/src/lib.rs	85% <100%> (+<1%)	⬆️
state-chain/pallets/cf-ingress-egress/src/mock.rs	98% <100%> (ø)
state-chain/pallets/cf-ingress-egress/src/tests.rs	99% <100%> (ø)
state-chain/pallets/cf-lp/src/lib.rs	69% <ø> (ø)
state-chain/traits/src/lib.rs	49% <ø> (ø)
state-chain/traits/src/mocks/deposit_handler.rs	83% <100%> (+1%)	⬆️
state-chain/runtime/src/chainflip.rs	53% <50%> (+1%)	⬆️
state-chain/pallets/cf-swapping/src/lib.rs	84% <82%> (-<1%)	⬇️
api/lib/src/lib.rs	31% <0%> (-<1%)	⬇️

... and 9 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[kylezs]

Cheers 👍