x/stake: Speed up handleMsgEditValidator

[ValarDragon]

This removes running the power update logic on handleMsgEditValidator,
as its unnecessary.

Closes #1815

• Linked to github-issue with discussion and accepted design
• Updated all relevant documentation (docs/) - n/a??
• Updated all relevant code comments
• Wrote tests - n/a?
• Added entries in PENDING.md that include links to the relevant issue or PR that most accurately describes the change.
• Updated cmd/gaia and examples/ - n/a

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[ValarDragon]

I didn't think it was worth the overhead of making a separate PR for these typo fixes, so I just included it here.

[ValarDragon]

I don't understand why this is causing an error in TestGaiadExport

=== RUN   TestGaiadExport
D[07-28|04:45:41.035] Commit synced                                commit="CommitID{[186 108 234 48 202 251 102 117 88 206 245 9 3 193 123 244 147 82 77 162]:1}"
unused CommitStoreLoader: KVStoreKey{0xc420209650, params}
FAIL	github.com/cosmos/cosmos-sdk/cmd/gaia/app	0.132s

[ValarDragon]

This is passing locally for me

[ValarDragon]

It passed on rerunning, I think it was a cache issue. https://circleci.com/gh/cosmos/cosmos-sdk/18848#queue-placeholder/containers/1

[rigelrozanski]

yeah it's the non-determinism

[rigelrozanski]

thanks