Remove 3rd native staking strategy from OETH Vault

[naddison36]

Changes

• Remove the 3rd Native Staking Strategy from the OETH Vault
• The SSV in the 3rd SSV Cluster can no longer be removed using the old withdrawSSV function as it was expected the cluster would have been migrated to ETH Payments by now. migrateClusterToETH needs to be used instead to return the left over SSV in the cluster. But this can't be called until the SSV Network is upgrade. This has now been pushed back to mid April.
• The 2nd Native Staking Strategy will remain until late May or early June when the validator consolidation has been completed. The strategy contract, unit tests, fork tests and hardhat tasks for all the Native Staking Strategies can be removed then.

Code Change Checklist

To be completed before internal review begins:

• The contract code is complete
• Executable deployment file
• Fork tests that test after the deployment file runs
• Unit tests *if needed
• The owner has done a full checklist review of the code + tests

Internal review:

• Two approvals by internal reviewers

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.30%. Comparing base (6114b09) to head (5119ef7).
⚠️ Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2866      +/-   ##
==========================================
- Coverage   55.26%   53.30%   -1.97%     
==========================================
  Files         112      112              
  Lines        4844     4844              
  Branches     1343     1343              
==========================================
- Hits         2677     2582      -95     
- Misses       2162     2257      +95     
  Partials        5        5              

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[sparrowDom]

LGTM, thanks for removing the obsolete defender action scripts
✅ the 3rd native staking strategy has only 10ˆ-8 ETH dust