refactor: rm legacySubspace from NewKeeper funcs

[johnnylarner]

Description

closes: IBCGO-27 [Linear]

GH: #5771

---

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[linear]

IBCGO-27 Remove legacy params subspace args from ibc keepers

[codecov]

Codecov Report

Attention: Patch coverage is 89.74359% with 4 lines in your changes missing coverage. Please review.

Project coverage is 56.80%. Comparing base (de2f70a) to head (82ef57d).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
modules/apps/callbacks/testing/simapp/app.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8476   +/-   ##
=======================================
  Coverage   56.80%   56.80%           
=======================================
  Files         299      296    -3     
  Lines       21521    21431   -90     
=======================================
- Hits        12225    12174   -51     
+ Misses       8738     8707   -31     
+ Partials      558      550    -8     

Flag	Coverage Δ
08-wasm	66.13% <ø> (ø)
e2e	1.18% <ø> (ø)
ibc-go	62.23% <89.74%> (+0.02%)	⬆️

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[DeshErBojhaa]

Great start.

Let's try to remove LigacySubspace field from the keepers (if possible).

Let's add an entry for it to changelog.

[johnnylarner]

Will add to the changelog

[gjermundgaraba]

Great job! It's so nice to finally get rid of all this deprecated stuff 🎉

I created a follow-up issue to remove the remaining legacy subspace references we have scattered around, as this PR fully solves the original issue now.