Describe the bug
When sending reporting data, the plugin currently sends the "site url" sometimes with and sometimes without the trailing slash, resulting in duplicated tracking entries.

To Reproduce
Steps to reproduce the behavior:

1. Set up the plugin on a new domain.
2. Check the domain sent for tracking events.

Expected behavior
The domain used for tracking should be consistent, never including a trailing slash.

Screenshots
If applicable, add screenshots to help explain your problem.

System Information (please complete the following information):

• PHP Version:
• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Plugin Version [e.g. 22]
• Device: [e.g. iPhone6]

Additional context

• Please add any additional information about the bug.

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Changelog entry

• Ensure domain sent for reporting is consistent by trimming any trailing slashes.

Acceptance criteria