[Tests-Only] Added acceptance tests for user:sync command with super/sub-strings in user usernames

[kiranparajuli589]

Description

Acceptance tests added for user:sync command covering:

• sync a user that is a substring of some other LDAP user
• sync a user that is a substring and superstring of some local user

Related Issue

owncloud/core#36597
owncloud/core#33293

How Has This Been Tested?

• 🤖

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Database schema changes (next release will require increase of minor version instead of patch)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:
• Changelog item, see TEMPLATE

[codecov]

Codecov Report

Merging #508 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #508   +/-   ##
=========================================
  Coverage     35.95%   35.95%           
  Complexity     1332     1332           
=========================================
  Files            31       31           
  Lines          3780     3780           
=========================================
  Hits           1359     1359           
  Misses         2421     2421

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[phil-davis]

@kiranparajuli589 before pushing changes, you can wait for the other PR to get merged.
There will be conflicts to resolve anyway, after that.