Enhance pre-commit hooks with flake8 linting

[Ygnas]

What this PR does / why we need it:
This PR implements the flake8 linter as a pre-commit hook to ensure code quality and adherence to style guidelines. It also addresses and fixes the issues identified by flake8.

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #1910

Checklist:

• Docs included if any changes are user facing

[andreyvelich]

Thank you for adding this @Ygnas!

It would be nice to add it for Katib as well: https://github.com/kubeflow/katib/blob/master/.pre-commit-config.yaml.

/lgtm
/assign @droctothorpe

[droctothorpe]

LGTM! Great job, @Ygnas! I freaking love pre-commit.

[droctothorpe]

/lgtm

[droctothorpe]

/approve

[andreyvelich]

/rerun-all

[coveralls]

Pull Request Test Coverage Report for Build 10263855792

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 33.486%

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Totals
Change from base Build 10252995442:	0.02%
Covered Lines:	3950
Relevant Lines:	11796

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💛 - Coveralls

[andreyvelich]

/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andreyvelich, droctothorpe

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