[UI] Monitoring Endpoint URL Handling

Percona Everest 1.5.0

Trailing slashes (/) in Monitoring Endpoint URLs prevent the URL from being added in Percona Everest 1.5.

When adding a Monitoring Endpoint, if the URL ends with a /, it is not added. This can cause confusion, as users may copy and paste URLs with a trailing slash.

Proposed Solution:
Automatically trim the trailing slash (/) or properly handle it to ensure the URL is accepted.

Notes:
- Reported by