refactor(ios): Xcode warning

[kumo01GitHub]

Platforms affected

iOS

Motivation and Context

To remove Xcode warning

Description

• remove unused variable locationServicesEnabledInstancePropertyAvailable
• explicitly mention 'self'

Testing

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[kumo01GitHub]

fix: #257 (comment)