Fix an issue where the wrong position would be used for app bubbles

The location was incorrectly being set to 'default' in one path
for new bubble launches. This could result in mis-matching location
on screen for bubble bar & the expanded view.

The fix is to pass null, so that the location is not changed through
this flow.

Bug: 425675028
Flag: com.android.wm.shell.enable_create_any_bubble
Test: manual - bubble google TV (or something that trampolines)
             - move bubble bar to the left side
             - re-bubble google TV
             => observe that bubble bar/expanded view remain on left
Test: atest BubbleControllerTest
Change-Id: Id156b69f9381e241b9ccb791c67cebdf32de2ddf