tests: Replace TransportClient by NodeClient

[rs-eliatra]

Description

[Describe what this change achieves]

• Category = Maintenance
• Why these changes are required?
  Check description in: Replace uses of deprecated TransportClient #1578

Issues Resolved

#1578

Testing

Testing done:

• unit testing

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[peternied]

This change is a little hard to review with out seeing #1638 merged. If you don't mind I'm going to review these changes in https://github.com/rs-eliatra/security/pull/11/files. Let me know if you have another recommendation.

thanks for rebasing after the other change was merged

[codecov-commenter]

Codecov Report

Merging #1660 (5bb38ec) into main (fc3842c) will decrease coverage by 0.92%.
The diff coverage is 50.48%.

@@             Coverage Diff              @@
##               main    #1660      +/-   ##
============================================
- Coverage     64.61%   63.68%   -0.93%     
+ Complexity     3217     3166      -51     
============================================
  Files           247      249       +2     
  Lines         17352    17481     +129     
  Branches       3082     3097      +15     
============================================
- Hits          11212    11133      -79     
- Misses         4594     4795     +201     
- Partials       1546     1553       +7     

Impacted Files	Coverage Δ
...g/opensearch/security/support/WildcardMatcher.java	61.03% <ø> (ø)
...a/org/opensearch/security/tools/SecurityAdmin.java	45.80% <39.14%> (-1.92%)	⬇️
...opensearch/security/filter/SecurityRestFilter.java	76.66% <66.66%> (+0.80%)	⬆️
...opensearch/security/rest/SecurityWhoAmIAction.java	78.37% <78.37%> (ø)
.../action/configupdate/ConfigUpdateNodeResponse.java	81.81% <83.33%> (-5.69%)	⬇️
...arch/security/rest/SecurityConfigUpdateAction.java	95.23% <95.23%> (ø)
.../opensearch/security/OpenSearchSecurityPlugin.java	79.54% <100.00%> (-1.39%)	⬇️
...rity/action/configupdate/ConfigUpdateResponse.java	64.28% <100.00%> (-35.72%)	⬇️
...ensearch/security/action/whoami/WhoAmIRequest.java	0.00% <0.00%> (-100.00%)	⬇️
...nsearch/security/action/whoami/WhoAmIResponse.java	0.00% <0.00%> (-82.86%)	⬇️
... and 22 more

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