Remove unused strings android_upgrading_apk and
android_upgrading_fstrim.

Last uses were removed in
commit a1131b1763efa56fe4fcaddf712a984a7d2d47da and
commit 0505aa09b2a0e788ba0554bc677f8c44b48745b1, respectively.

Test: m
Bug: 251903639
Change-Id: I9af6914414ce9be047e89b44587d962b574ae47b
173 files changed