Revert "internal/graphicscommand: bug fix: flush image buffers"
Revert "internal/graphicscommand: bug fix: flush image buffers"

This reverts commit d6910eb9aba3cbd7a9d7267da1e386d2c319cbdf.

Reason: The wasm flakiness occured again

Updates #2391
Updates #2423

hajimehoshi/ebiten,hajimehoshi/ebiten