Fix `Transformer` not querying `isVideoFormatSupported`

Transformer uses a `CapturingEncoderFactory`. If the method
`isVideoFormatSupported()` is not implemented, it'll default to true despite
the underlying delegate `EncoderFactory` might report false

PiperOrigin-RevId: 946946378
(cherry picked from commit aed0e2d361b364eb9a3f0a12dfb6e1d7316ad8dd)