Change the query parameters 'size' and 'search' of 'getDestinations' request to be optional

[ftianli-amzn]

Issue #, if available:

Description of changes:

This is a mistake made during the migration to new Kibana platform (PR #209)

Current behavior:
Destinations list fails to refresh after removing a destination.

Reason:
The route validation for the front-end getDestinations request is not correct.
No query parameters comes with the request when getting the destinations list after removing a destination.

• Change the query parameters 'size' and 'search' of 'getDestinations' request to be optional in the router.

After the change, destinations list can be refreshed after removing a destination.

Test Suites: 6 skipped, 83 passed, 83 of 89 total
Tests:       20 skipped, 385 passed, 405 total
Snapshots:   135 passed, 135 total
Time:        61.738 s
Ran all test suites.
✨  Done in 62.99s.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.