fix(analyze_boot): wrong return code analyze boot

[AliyevH]

Returning string at the end causes sys.exit to exit with non zero code. Just removing return statement.

fixes: gh-4245

Proposed Commit Message

<type>(optional scope): <summary>  # no more than 72 characters

A description of what the change being made is and why it is being
made if the summary line is insufficient.  This should be wrapped at
72 characters.

If you need to write multiple paragraphs, feel free.

Fixes GH-NNNNN (GitHub Issue number. Remove line if irrelevant)
LP: #NNNNNN (Launchpad bug number. Remove line if irrelevant)

Additional Context

Test Steps

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)