Selected elements are not cleared between page changes

[w33ble]

Kibana version: discovered in master, but probably 6.7+

Original install method (e.g. download page, yum, from source, etc.): Clone repo

Describe the bug:

When you select an element and change the page, the element is still selected when you go back to the original page. The sidebar is also the workpad sidebar, I think because the aeroelastic state is getting out of sync with the application's state.

Steps to reproduce:

1. On a workpad with at least 2 pages, select and element
2. Change to another page while that element is still selected
3. Select an element on the new page (this step isn't really required)
4. Go back to the first page you were on

Expected behavior:

When you change pages, none of the elements should remain selected.

Screenshots (if relevant):

[elasticmachine]

Pinging @elastic/kibana-canvas