[ios] Fix call to logLaunchMetricsWithStartupInformation

self.appState.connectedScenes in a multi window environment gets the
correct number of scenes only at InitStageFinal.

This CL moves call of
[MetricsMediator
       logLaunchMetricsWithStartupInformation:connectedScenes:];
from: InitStageFirstRun to: InitStageFinal

In this way we are able to collect metrics for all connected scenes
(even if we have more than one).

Fixed: 337021936
Change-Id: Ib47b51ea73b02dfe3aedd3f0d7c7cfb14058fa23
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5490665
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Federica Germinario <fedegermi@google.com>
Cr-Commit-Position: refs/heads/main@{#1293656}