[FIXED JENKINS-21023] Rewrote WorkspaceCleanupThread to determine where workspaces for known items should be, rather than looking for directories that look like they might be workspaces.
One key advantage is that this correctly handles the new default workspace location on the master.
Another is that this allows folders to be correctly skipped, and jobs in folders to be correctly deleted.
A subtler advantage would be handling of configured nondefault workspace locations, and compatibility with WorkspaceLocator.
(Orphaned workspaces from deleted jobs are not removed, but these were not removed before either.)

Update Messages_ru.properties

Fixed typo. Unstable in russian is "Нестабильно", not "Настабильно".

[FIXED JENKINS-19832] Added a descriptor for GlobalSecurityConfiguration. This enables helps on Configure Global Security page.

Fix link to TCP slave port configuration.

This will prevent people from accidentally deleting the project when they are trying to bulk-delete buid records

[FIXED JENKINS-21612] fixed wrong CSS class for f:combobox.

If it's significant enough to introduce regressions, it's significant enough for the changelog.

This is sort of a cosmetic change, the script also worked with string
comparison.

[JENKINS-21474] Fix NPE in View.getComputers()

Fix 2 bugs in translation tools + Improve French translations

waiting for

Remove unnecessary executable bits on source files

Fix windows-slaves-plugin

2669e4a8 extracted windows-slaves code
to a separate plugin.
However in the process, it introduced a dependency conflict.
core -> j-interop -> jcifs (1.2.19)
whereas
windows-slaves-plugin -> ... -> jcifs (1.3.17-kohsuke-1)

This was causing NoSuchMethodError while launching windows slaves

- Division by zero --> Error
- Properties with space

Introduce `OfflineCause.UserCause`

Let -Dignore.random.failures work on UpdateCenterTest, which is currently failing and so blocking validated merge.