Fix bug deprecation message retrieval

[Dilhasha]

Purpose

Fix issue in deprecation message retrieval.

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

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 75.05%. Comparing base (006eb9d) to head (cd53af1).
Report is 60 commits behind head on master.

Files with missing lines	Patch %	Lines
...java/io/ballerina/projects/internal/BalaFiles.java	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #43920      +/-   ##
============================================
- Coverage     75.06%   75.05%   -0.01%     
+ Complexity    57516    57508       -8     
============================================
  Files          3540     3540              
  Lines        222373   222375       +2     
  Branches      28835    28836       +1     
============================================
- Hits         166922   166905      -17     
- Misses        46184    46204      +20     
+ Partials       9267     9266       -1     

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[azinneera]

if (fileContents.isEmpty()) {
    return "";
} 
return fileContents.substring(0, fileContents.length() - 1);