Android: Update list of isolated splits when a DFM is installed

Will hopefully fix VR DFM install flow on Android T+.

This also removes the need to pass a Context to isIsolatedSplitInstalled().

Bug: b/258453540
Change-Id: I06f7fb4f6670ba4b962e298618c3dd8256ff2cf1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4027111


Reviewed-by: Fred Mello <fredmello@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1072302}