fix: do not flatten events attributes by event types (backport #14691)

[mergify]

This is an automatic backport of pull request #14691 done by Mergify.
Cherry-pick of d5d39c0 has failed:

On branch mergify/bp/release/v0.47.x/pr-14691
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Changes to be committed:
	modified:   math/dec_test.go
	modified:   math/int_test.go
	modified:   types/events.go
	modified:   types/events_test.go
	modified:   types/result_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[tac0turtle]

We should notify relayers of this.

[tac0turtle]

merging for now, pinged the ibc team.

cc @jackzampolin @adizere for visibility

[adizere]

It's difficult for me to say if this will break relayers (in addition to the even encoding breaking changes Tendermint v0.37.0). Should we expect it to be a breaking change and do tests? Thanks!

[tac0turtle]

@julienrbrt want to cut a new rc and ill update ibc to see if things break?

[julienrbrt]

@julienrbrt want to cut a new rc and ill update ibc to see if things break?

Sure thing, but isn't it better to have an RC2 with #14713 and the IAVL changes?
You can always use a pseudo version based on the latest commit (as I type it is v0.47.0-rc1.0.20230124153503-bf38ebfcd5b1).