Refactor LinearSearch to simplify null checks

[YERRA-CHARAN]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new algorithms include a corresponding test class that validates their functionality.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[YERRA-CHARAN]

I had got the error and also fixed it please try with these changes. I think this one will help the upcoming contributors to understand the linear search more easily.
Thankyou.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.52%. Comparing base (49f9e1a) to head (cf340ea).

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/searches/LinearSearch.java	33.33%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #7368   +/-   ##
=========================================
  Coverage     79.51%   79.52%           
  Complexity     7142     7142           
=========================================
  Files           796      796           
  Lines         23359    23358    -1     
  Branches       4596     4596           
=========================================
  Hits          18575    18575           
- Misses         4046     4047    +1     
+ Partials        738      736    -2     

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