Fix service type inference

[rdhananjaya]

Purpose

Improve service type inference

Fixes #33873

Approach

Describe how you are implementing the solutions along with the design details.

Samples

Provide high-level details about the samples related to this feature.

Remarks

List any other known issues, related PRs, TODO items, or any other notes related to the PR.

Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[codecov]

Codecov Report

Merging #33842 (548f055) into stage-slbeta4 (2b22827) will decrease coverage by 0.14%.
The diff coverage is 77.58%.

@@                 Coverage Diff                 @@
##             stage-slbeta4   #33842      +/-   ##
===================================================
- Coverage            71.04%   70.90%   -0.15%     
+ Complexity           43239    43168      -71     
===================================================
  Files                 3139     3139              
  Lines               175016   175075      +59     
  Branches             22592    22608      +16     
===================================================
- Hits                124345   124129     -216     
- Misses               43569    43871     +302     
+ Partials              7102     7075      -27     

Impacted Files	Coverage Δ
...wso2/ballerinalang/compiler/tree/BLangService.java	50.00% <ø> (ø)
.../compiler/semantics/analyzer/SemanticAnalyzer.java	83.97% <73.46%> (-0.29%)	⬇️
...erinalang/util/diagnostic/DiagnosticErrorCode.java	99.82% <100.00%> (+<0.01%)	⬆️
...llerinalang/compiler/semantics/analyzer/Types.java	79.99% <100.00%> (+0.03%)	⬆️
...inalang/testerina/core/AssertionDiffEvaluator.java	0.00% <0.00%> (-84.13%)	⬇️
...erinalang/testerina/natives/mock/FunctionMock.java	0.00% <0.00%> (-82.54%)	⬇️
.../org/ballerinalang/testerina/natives/Executor.java	0.00% <0.00%> (-72.42%)	⬇️
...llerinalang/testerina/core/BallerinaTypeCheck.java	0.00% <0.00%> (-71.43%)	⬇️
...erinalang/testerina/natives/mock/MockRegistry.java	0.00% <0.00%> (-57.15%)	⬇️
...rinalang/testerina/natives/mock/MockConstants.java	0.00% <0.00%> (-50.00%)	⬇️
... and 16 more

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[shafreenAnfar]

Out of curiosity, do we still use @tainted ?

[hasithaa]

It is not needed. Should be a copied code.