Problem: gravity-bridge is not audited

[yihuang]

Solution:

• remove it for mainnet launch, could be added back later in an optional way
• SendToEthereum native call always return an error.

ref: #168

Since the new binary is required by devops team for testnet, we could strip it for now, add discuss how to add it back in a conditional way later.

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PR Checklist:

• Have you read the CONTRIBUTING.md?
• Does your PR follow the C4 patch requirements?
• Have you rebased your work on top of the latest master?
• Have you checked your code compiles? (make)
• Have you included tests for any non-trivial functionality?
• Have you checked your code passes the unit tests? (make test)
• Have you checked your code formatting is correct? (go fmt)
• Have you checked your basic code style is fine? (golangci-lint run)
• If you added any dependencies, have you checked they do not contain any known vulnerabilities? (go list -json -m all | nancy sleuth)
• If your changes affect the client infrastructure, have you run the integration test?
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• If your code changes public APIs, have you incremented the crate version numbers and documented your changes in the CHANGELOG.md?
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Thank you for your code, it's appreciated! :)

[codecov]

Codecov Report

Merging #171 (ac8dd24) into main (3ea70c5) will increase coverage by 5.11%.
The diff coverage is 54.48%.

@@            Coverage Diff             @@
##             main     #171      +/-   ##
==========================================
+ Coverage   21.51%   26.63%   +5.11%     
==========================================
  Files          27       33       +6     
  Lines        1729     2328     +599     
==========================================
+ Hits          372      620     +248     
- Misses       1324     1662     +338     
- Partials       33       46      +13     

Impacted Files	Coverage Δ
app/prefix.go	0.00% <0.00%> (ø)
app/test_helpers.go	0.00% <0.00%> (ø)
x/cronos/keeper/grpc_query.go	0.00% <0.00%> (ø)
x/cronos/keeper/msg_server.go	5.00% <0.00%> (-1.46%)	⬇️
x/cronos/module.go	59.64% <0.00%> (-2.17%)	⬇️
x/cronos/types/codec.go	0.00% <0.00%> (ø)
x/cronos/types/events.go	0.00% <ø> (ø)
x/cronos/types/params.go	57.35% <ø> (+3.78%)	⬆️
x/cronos/types/proposal.go	11.11% <ø> (ø)
x/cronos/types/query.pb.gw.go	0.00% <ø> (ø)
... and 18 more

---

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[thomas-nguy]

Lgtm,

The title of the PR is a bit weird though, maybe it should be just "Feature: remove gravity bridge" or "Problem: gravity-bridge is not audited"

[yihuang]

Lgtm,

The title of the PR is a bit weird though, maybe it should be just "Feature: remove gravity bridge" or "Problem: gravity-bridge is not audited"

thanks, "gravity-bridge is not audited" is better.