adapt shutdown signal in solo init function

[libotony]

Description

• [x] Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [x] Start solo, press control + C, should be shutdown immediately

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] New and existing E2E tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 12.50000% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 61.90%. Comparing base (74e275d) to head (14773f1).

Files	Patch %	Lines
cmd/thor/solo/solo.go	12.50%	6 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #750 +/- ## ========================================== - Coverage 61.91% 61.90% -0.02% ========================================== Files 199 199 Lines 18315 18318 +3 ========================================== Hits 11339 11339 - Misses 5874 5877 +3 Partials 1102 1102 ```

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