Don't report suspicious periodic sync removal for gone users

Bug: 64536115
Test: Manual: Create secondary user, add a google account, remove the
user -> no wtf shown.
Test: Manual: Add a google account on user 0, remove it ->
no wtf shown.
Test: Manual: Add a google account, remove gmail-ls sync with
"requestsync remove-periodic" -> wtf shown

Change-Id: I136c605612337a681ccb3305d2352769167e159b