Fix: pre-commit and tox issues

Fix: pre-commit and tox issues

pre-commit and tox issues need to be fixed for tox-verify
GHA tox-verify to work correctly.

- shellcheck errors:
  SC3040 (warning): In POSIX sh, set option pipefail is undefined.
  SC3037 (warning): In POSIX sh, echo flags are undefined.
  SC2086 (info): Double quote to prevent globbing and word splitting.
  SC2004 (style): $/${} is unnecessary on arithmetic variables.
- flake: E501 line too long
- pydocsytle errors:
  D103: Missing docstring in public function
  D100: Missing docstring in public module
- write-good errors remove passive voice
- Fixes bandit: CWE: CWE-20 (https://cwe.mitre.org/data/definitions/20.html)
  Using lxml.etree.parse to parse untrusted XML data is known to be
  vulnerable to XML attacks. Replace lxml.etree.parse with its
  defusedxml equivalent function
  Ref: https://rules.sonarsource.com/python/RSPEC-2755

Issue: LF-JIRA RELENG-4742
Change-Id: I635281bc39ebb1157df13dde6809c2809af8c1d4
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>