fix: mark loadBitmap canvas as willReadFrequently #18671

All 209 tests pass in 2s

1 files ±0 55 suites ±0 2s ⏱️ -1s
209 tests ±0 209 ✅ ±0 0 💤 ±0 0 ❌ ±0
279 runs ±0 279 ✅ ±0 0 💤 ±0 0 ❌ ±0

Results for commit 1be24de. ± Comparison against earlier commit 981844b.