Skip both empty line and also new line in the output of portstat.

[ysmanman]

Description of PR

#7560 was closed with #7537. However, we still observed the the issue in our testing even with #7537. The fix in #7537 is incomplete because it only skips new line, but fails to skip empty line. Fix the issue in this PR to skip both new line and empty line.

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 201911
• 202012
• 202205

Approach

What is the motivation for this PR?

How did you do it?

How did you verify/test it?

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[wangxin]

The pre-commit check detected issues in the files touched by this pull request.
The detected issues may be old or new. For new issues, please try to fix them.

For old issues, it is not mandatory to fix them because they were not caused by this change. It is unfair to blame
author of this pull request. But if you can take extra effort to fix the old issues as well, that would be great!

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/common/portstat_utilities.py:69:29: E261 at least two spaces before inline comment

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[ysmanman]

Add @arlakshm @wenyiz2021 for visibility.

[wenyiz2021]

thanks @ysmanman for this fix!
sorry for missing to check the final fix for PR#7537. I was doing [separation_line_number+1:reminder_line_number-1] and skipped all last 3 lines in my pdb.