fix(yaml): Don't remove lines including U+3000 (#12305)

Co-authored-by: fisker Cheung <lionkay@gmail.com>

changelog_unreleased/yaml/12305.md

@@ -0,0 +1,15 @@
+#### Fix unexpected deletion of block-literal lines which starts with U+3000 (#12305 by @Quramy)
+
+<!-- prettier-ignore -->
+```yaml
+# Input 
+block_with_ideographic_space: |
+  　line-content # This line starts with U+3000
+
+# Prettier stable
+block_with_ideographic_space: |
+
+// Prettier main
+block_with_ideographic_space: |
+  　line-content # This line starts with U+3000
+```