[Spring Cleanup] Remove spring dependencies in DCR endpoint

[lashinijay]

Purpose

This PR removes dependencies and usages of the Spring framework in the DCR REST API.

Related Issue(s)

• Remove Spring dependencies from Identity Server applications wso2/product-is#21159

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 55.25%. Comparing base (dc41ff9) to head (d5062fb).
Report is 12 commits behind head on master.

Files with missing lines	Patch %	Lines
.../endpoint/factories/RegisterApiServiceFactory.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2627      +/-   ##
============================================
+ Coverage     53.35%   55.25%   +1.90%     
+ Complexity     8589     8199     -390     
============================================
  Files           632      631       -1     
  Lines         52956    47471    -5485     
  Branches       9069     8375     -694     
============================================
- Hits          28253    26232    -2021     
+ Misses        20597    17491    -3106     
+ Partials       4106     3748     -358     

Flag	Coverage Δ
unit	38.66% <50.00%> (+0.06%)	⬆️

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[lashinijay]

Duplicate of #2631