js/ui: Always use namespace for animation modes

Clutter.Animation doesn't contain any animation modes, they live in
Clutter.AnimationMode. The places we did `Clutter.Animation.WHATEVER`
just evaluated to `undefined`. Thus, use the correct namespace for the
animation mode enums.

GNOME/gnome-shell!1199
9 jobs for !1199 with wip/remove-clutter-state-alpha-animation in 9 minutes and 47 seconds (queued for 2 seconds)
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Status Job ID Name Coverage
  Review
passed #672122
check_commit_log

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passed #672124
eslint

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passed #672123
js_check

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passed #672126
no_template_check

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passed #672125
potfile_check

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  Build
passed #672127
build

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passed #672128
flatpak
flatpak

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  Test
passed #672129
test

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passed #672130
test-pot

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