[Reporting] When capturing screenshots only set viewport size for print-layout reports

[jloleysens]

When taking a screenshot in Chromium we setViewport just before we get to the step of taking the screenshots. This can lead to a race condition with browser reflows (mitigated in this PR #123820).

We can mitigate this further by only calling for viewport resizing when it is actually necessary: PDF print-optimised reports. In this type of report we need to set the height based on the number visualisations which is only known once the browser is open and we have had a chance to count the visualisations. One alternative could be that we send a count of the visualisations on the client request but this could create a race-condition between generating a report and updates a user may make (e.g., removing a vis) in that time.

Full context of behind this reasoning: #123820 (comment)

[elasticmachine]

Pinging @elastic/kibana-reporting-services (Team:Reporting Services)

[elasticmachine]

Pinging @elastic/kibana-app-services (Team:AppServicesUx)

[jloleysens]

CC @tsullivan

[tsullivan]

We need to aggressively avoid resize events before capturing a screenshot. The app can not uphold its contract with reporting that all panels will be visible, if there were instances of resizing. #131605 (comment)

[tsullivan]

We need to aggressively avoid resize events before capturing a screenshot. The app can not uphold its contract with reporting that all panels will be visible, if there were instances of resizing. #131605 (comment)

In #131877, I am adding debug logging to track when resizing happens. Based on a little bit of testing, resizing is actually just happening for print layout PDF reports.

So, I think this issue is actually not urgent, since we're actively working on re-implementing print layout PDF reports.

[tsullivan]

Duplicate of #131111 and fixed in that issue