modified_on date-time is not updating in update function

[vaibhavkumar-sf]

Describe the bug
modified_on date-time is not updating in update function. Updating correctly via save function, but not in update / updateAll / updateByID and so on..

To Reproduce
Steps to reproduce the behavior:

1. hit any API to update data in a simple table (having no triggeres to update modified_on), having created_on , modified_on columns..
2. see, modified_on value is not auto-updating.

Expected behavior
I want modified_on to be auto updated to the current date-time

Screenshots
Few work was dont for that

But this was reverted in next commit :
1307aa0

But not sure why reverted adding current dates in modified_on ? is this value to be updated from DATABASE Trigger ? Or from our APIs ?

Additional context
Add any other context about the problem here.