Revert DatabaseOpenDialog to be always on top on Linux

[droidmonkey]

Fixes regression due to issues with dialogs appearing above other windows on some Linux Desktop Envs.

Type of change

• ✅ Bug fix (non-breaking change that fixes an issue)

[codecov-commenter]

Codecov Report

Merging #7771 (262b517) into develop (2b8d670) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop    #7771      +/-   ##
===========================================
- Coverage    64.29%   64.29%   -0.00%     
===========================================
  Files          339      339              
  Lines        43451    43455       +4     
===========================================
+ Hits         27936    27938       +2     
- Misses       15515    15517       +2     

Impacted Files	Coverage Δ
src/gui/DatabaseOpenDialog.cpp	60.75% <100.00%> (+1.52%)	⬆️
src/core/Entry.cpp	82.59% <0.00%> (-0.20%)	⬇️

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[phoerious]

Ugly, but whatever. Will revisit when we have quick unlock.