Fix updating Azure connection string && increase credentials max_length

[Marishka17]

Motivation and context

PR fixes the issue described in ticket 470

How has this been tested?

Manually

Checklist

• I submit my changes into the develop branch
• I have created a changelog fragment
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (see GitHub docs)
• I have increased versions of npm packages if it is necessary
  (cvat-canvas,
  cvat-core,
  cvat-data and
  cvat-ui)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.

[codecov]

Codecov Report

Merging #7336 (a02bcd8) into develop (64d6d7a) will increase coverage by 0.00%.
Report is 1 commits behind head on develop.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #7336   +/-   ##
========================================
  Coverage    82.96%   82.97%           
========================================
  Files          373      373           
  Lines        39601    39601           
  Branches      3704     3704           
========================================
+ Hits         32856    32857    +1     
+ Misses        6745     6744    -1     

Components	Coverage Δ
cvat-ui	78.45% <ø> (ø)
cvat-server	87.11% <100.00%> (+<0.01%)	⬆️