[BP: release/v6 <- #222] feat: add storage leak test

[mergify]

Previously, flight packets were retained in the module's storage after a packet timeout. Now, flight packets are correctly removed when they timeout. An additional test was also added to verify that flight packets are correctly removed and not retained in storage after a timeout.

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This is an automatic backport of pull request #222 done by Mergify.

[mergify]

Cherry-pick of 64c5cd5 has failed:

On branch mergify/bp/release/v6/pr-222
Your branch is up to date with 'origin/release/v6'.

You are currently cherry-picking commit 64c5cd5.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   middleware/packet-forward-middleware/e2e/storage_leak_test.go
	modified:   middleware/packet-forward-middleware/packetforward/ibc_middleware.go

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   .github/workflows/packet-forward-middleware.yml
	both modified:   middleware/packet-forward-middleware/Makefile

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