Use proper method to format absolute timestamp

[MorrisJobke]

Ref #8375

[skjnldsv]

Code makes sense

[codecov]

Codecov Report

Merging #8782 into master will decrease coverage by 20.49%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #8782      +/-   ##
============================================
- Coverage     51.87%   31.37%   -20.5%     
+ Complexity    25380    25376       -4     
============================================
  Files          1608     1608              
  Lines         95157    95151       -6     
  Branches       1377     1377              
============================================
- Hits          49366    29858   -19508     
- Misses        45791    65293   +19502

Impacted Files	Coverage Δ	Complexity Δ
lib/private/legacy/util.php	25.74% <ø> (-33.04%)	240 <0> (-4)
settings/templates/settings/admin/server.php	0% <0%> (ø)	0 <0> (ø)	⬇️
lib/private/TagManager.php	0% <0%> (-100%)	4% <0%> (ø)
apps/user_ldap/lib/LDAPUtility.php	0% <0%> (-100%)	1% <0%> (ø)
...s/dav/lib/Connector/Sabre/Exception/FileLocked.php	0% <0%> (-100%)	3% <0%> (ø)
lib/private/Share20/Hooks.php	0% <0%> (-100%)	3% <0%> (ø)
lib/private/Files/Mount/CacheMountProvider.php	0% <0%> (-100%)	4% <0%> (ø)
lib/private/Accounts/Hooks.php	0% <0%> (-100%)	14% <0%> (ø)
...public/AppFramework/OCS/OCSBadRequestException.php	0% <0%> (-100%)	1% <0%> (ø)
...yBuilder/FunctionBuilder/SqliteFunctionBuilder.php	0% <0%> (-100%)	1% <0%> (ø)
... and 374 more