[Infra UI] Process tab flaky test fix- Wait for page loading (#165440)

Closes #160796 

## Summary

As we see in the picture from the failed build we are trying to check
the values when there are still spinners on the screen (so the data is
still loading).

<img width="1791" alt="image"
src="94608e6b-21b1-4435-9cee-efbf5a57f4ac">


To fix that I am now waiting for the page to load. This PR will be
backported to fix the issue in 8.9 and I will add a follow-up PR
(https://github.com/elastic/kibana/pull/165303) for the same fix in node
details tests.


[Build](https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/3035)

x-pack/test/functional/apps/infra/hosts_view.ts

@@ -344,6 +344,7 @@ export default ({ getPageObjects, getService }: FtrProviderContext) => {
       describe('Processes Tab', () => {
         it('should render processes tab and with Total Value summary', async () => {
           await pageObjects.infraHostsView.clickProcessesFlyoutTab();
+          await pageObjects.header.waitUntilLoadingHasFinished();
           const processesTotalValue =
             await pageObjects.infraHostsView.getProcessesTabContentTotalValue();
           const processValue = await processesTotalValue.getVisibleText();