Adjust ListTool response format

[jackiehanyang]

Description

Adjust ListTool response format to fix Request failed to get to the server (status code: 502) error when calling ListTool API

Also, adjust exception type for GetTool when there's no such tool. Now it returns 404 when no tool found

{
	"error": {
		"root_cause": [
			{
				"type": "status_exception",
				"reason": "Failed to find tool information with the provided tool name: CatIndexTo"
			}
		],
		"type": "status_exception",
		"reason": "Failed to find tool information with the provided tool name: CatIndexTo"
	},
	"status": 404
}

Issues Resolved

[List any issues this PR will resolve]

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (38b51f2) 82.63% compared to head (21070c9) 82.63%.
Report is 1 commits behind head on main.

❗ Current head 21070c9 differs from pull request most recent head 682166d. Consider uploading reports for the commit 682166d to get more accurate results

Files	Patch %	Lines
...rg/opensearch/ml/tools/GetToolTransportAction.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1887      +/-   ##
============================================
- Coverage     82.63%   82.63%   -0.01%     
  Complexity     5391     5391              
============================================
  Files           521      521              
  Lines         21724    21727       +3     
  Branches       2211     2212       +1     
============================================
+ Hits          17952    17954       +2     
- Misses         2873     2874       +1     
  Partials        899      899              

Flag	Coverage Δ
ml-commons	82.63% <75.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.