"In Use" and "Not In Use" suspension preferences could prevent computing indefinitely

[Vulpine05]

Describe the bug
BOINC has the option to suspend computer usage in two ways: When the computer is in use (IU), and when it is not in use (NIU). It is possible to enable suspension for both IU and NIU at the same time. It is also possible to set the values for each such that BOINC will never work on any tasks.

Steps To Reproduce

1. Open BOINC Manager->Options->Preferences.
2. Set IU time to 0.08, and NIU to 0.05 minutes. Save changes.

Expected behavior
A message should let the user know to change the settings, and these settings should not be saved.

System Information

• OS: Windows 10
• BOINC Version: 7.20.2, but I have seen this in earlier versions.

Additional context
This bug can occur in three locations:

• Manager: Changing settings in Options->Preferences - PR [Manager] [Advanced View] Add warning message in preferences for suspension #4955
• Client: Reading global_prefs_override.xml that a user may have manually edited. - PR [Client] Add alert if idle time to resume computing is greater than idle time to suspend computing #5270
• Web: User can modify computing preferences from a project.

[Vulpine05]

I had started working on the Manger change via #4634. I should be able to fix this in the Manager and Client. I think the fix for the client will prevent any web preferences from propagating to a client, but having an error message when saving web preferences would be better.

With that said, I am not familiar with php. Also, even if I figure out how to fix it via web, I don't know how to test and verify. If anyone is willing and able to do one or the other, please let me know.

[davidpanderson]

I don't think this is necessary.