Need to fix Coding Standards in flag bookmark sub module

Nikolay Shapovalov → made their first commit to this issue’s fork.

Thanks for you MR.
There are 382 violations in the flag code base.
MR fix all violations for flag_bookmark sub module.

FILE: ...odules/flag_bookmark/tests/src/Kernel/FlagBookmarkInstallUninstallTest.php
--------------------------------------------------------------------------------
FOUND 2 ERRORS AFFECTING 2 LINES
--------------------------------------------------------------------------------
 16 | ERROR | [x] Missing function doc comment
    |       |     (Drupal.Commenting.FunctionComment.Missing)
 36 | ERROR | [x] Missing function doc comment
    |       |     (Drupal.Commenting.FunctionComment.Missing)

I am not sure if we need merge this as separate issue, or combine with others.

Already fixed in https://git.drupalcode.org/project/flag/-/merge_requests/93