Fixes DagProcessor stats log | process duration changed to use time.monotonic

[ayush3singh]

Fixes #50317

Why

Log statement

DAG File Processing stats captured 'Current Duration' and 'Last Duration' and was using time.time() to calculate the duration of processing a DAG , PR changed to time.monotonic() for process start_time and then the log statement stated comparing unix timestamp to monotonic counter which gave wrong stats as shown below

Fix

This Fix changes the time.time() calls to use time.monotonic() and it fixes the issue as shown below:

[boring-cyborg]

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[ayush3singh]

@tirkarthi Please review

Thanks for all the help

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.

[github-actions]

Backport successfully created: v3-0-test

Status	Branch	Result
✅	v3-0-test