Support secondary_user_on_secondary_display in CtsToastLegacyTestCases

Test fixes include:
- AndroidTest.xml : add secondary_user_on_secondary_display option
- BaseToastTest.java : Previously, display 0 was always specified.
But, for the secondary_user_onsecondary_display user type,
We need to target the id of the display used by the secondary user.

Bug: 365112510
Flag: TEST_ONLY
Test: atest CtsToastLegacyTestCases
      atest CtsToastLegacyTestCases --user-type secondary_user
      atest CtsToastLegacyTestCases --user-type secondary_user_on_secondary_display
(cherry picked from https://partner-android-review.googlesource.com/q/commit:2bbe4367be87094c357bd507fc5a85b5a5e6a150)

Change-Id: I9d160e5fa6b5288e3929b16ceed4abed3ca25d24