Show updated Speed Label on Wifi detail page.

Fixes a bug where the detail page sometimes doesn't show a speed label
even when WifiSettings shows it. WifiSettings stores its connected
AccessPoint in a bundle on page load and connect. If that AccessPoint's
score cache doesn't have a score yet, it won't (can't) store it in the
bundle. If the score cache is then updated, it will display a score in
WifiSettings, but since the bundle has already been saved, the
AccessPoint that WifiNetworkDetailPage receives will not have a score.

This change modifies the preference to store the bundle only once the
user clicks the preference, so the detail page will be in sync with
WifiSettings.

Bug: 67607122
Test: manual
Change-Id: I6b33129b5a03b0e3e6d6e48ea48726e8dbe840b9