Remove some unused code

[maurelian]

Description

Some small changes:

1. Removes an unused import
2. Removes unused gas testing utils
3. Formats an md document (this was just a result of running yarn lint in the root)

[changeset-bot]

🦋 Changeset detected

Latest commit: 4710779

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@eth-optimism/contracts	Patch
@eth-optimism/batch-submitter	Patch
@eth-optimism/data-transport-layer	Patch
@eth-optimism/message-relayer	Patch
@eth-optimism/sdk	Patch

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[codecov-commenter]

Codecov Report

Merging #2133 (4710779) into develop (849ec8c) will increase coverage by 0.70%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #2133      +/-   ##
===========================================
+ Coverage    72.96%   73.66%   +0.70%     
===========================================
  Files           85       67      -18     
  Lines         2918     2187     -731     
  Branches       496      327     -169     
===========================================
- Hits          2129     1611     -518     
+ Misses         789      576     -213     

Flag	Coverage Δ
batch-submitter	62.63% <ø> (ø)
contracts	90.48% <ø> (ø)
core-utils	59.94% <ø> (ø)
data-transport-layer	37.74% <ø> (ø)
message-relayer	?
sdk	?

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Impacted Files	Coverage Δ
...ontracts/libraries/bridge/Lib_CrossDomainUtils.sol	100.00% <ø> (ø)
packages/sdk/src/adapters/standard-bridge.ts
packages/message-relayer/src/relay-tx.ts
packages/sdk/src/utils/index.ts
packages/sdk/src/utils/coercion.ts
packages/message-relayer/hardhat.config.ts
packages/sdk/src/adapters/eth-bridge.ts
packages/sdk/src/utils/message-encoding.ts
packages/sdk/src/index.ts
packages/sdk/src/cross-chain-messenger.ts
... and 9 more

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[smartcontracts]

Gotta love getting rid of code

[smartcontracts]

Ah damn, that's a flaky test. Will fix. https://github.com/ethereum-optimism/optimism/runs/5071586801?check_suite_focus=true#step:10:1559