Refactor i18n Consistency Checker Workflow for Improved Efficiency

[yuhattor]

This pull request primarily focuses on the refactoring of the .github/workflows/i18n-consistency-checker.yaml file. The changes include the removal of the Check issue.md existence step and the integration of its functionality into the Create issue step. Additionally, commented-out code related to creating a new issue or commenting on an existing one has been removed.

Refactoring of .github/workflows/i18n-consistency-checker.yaml:

• Removed the Check issue.md existence step, which was previously responsible for checking the existence of the issue.md file. This functionality has now been integrated into the Create issue step with the addition of a conditional check for the existence of the issue.md file.
• Removed commented-out code that was previously used to create a new issue or comment on an existing one. This helps to declutter the codebase and remove potential confusion.

[yuhattor]

@spier I updated a bit. Please take a look at this.
#586