Added unit-tests to cover all possible tags from preferences

[ashishkumar468]

Description (required)

Added unit-test cases for FileMetadataUtils

What changes did you make and why?

Added unit-tests to cover all possible tags from preferences

[codecov-io]

Codecov Report

Merging #3253 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #3253      +/-   ##
=========================================
+ Coverage    6.15%    6.2%   +0.05%     
=========================================
  Files         270     270              
  Lines       11608   11608              
  Branches      906     906              
=========================================
+ Hits          714     720       +6     
+ Misses      10839   10833       -6     
  Partials       55      55

Impacted Files	Coverage Δ
.../fr/free/nrw/commons/upload/FileMetadataUtils.java	72.72% <0%> (+54.54%)	⬆️

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