Code formatting issue with line length

Describe the bug

@msivasubramaniaan, I found the cause of bug #855. It's not related to a schema but to the number of characters. This code doesn't format correctly if any of the first 3 lines have an extra character.

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
    bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb:
        ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc:
            error: true

Expected Behavior

Ext should format code correctly, regardless of line length.

Current Behavior

Adding a character to the 3rd line causes this incorrect format.

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
    bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb:
        ? cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccX
        : error: true

Steps to Reproduce

1. Open VSCode and use the provided code
2. Add a character to the first 3 lines
3. Save or format the code.

Environment

• Windows
• Mac
• Linux
• other (please specify)

vscode: v1.78.2
yaml ext: v1.13.0

Start by reproducing the formatting problem in VSCode with the YAML extension using the sample configuration and the stated version information. Trace the YAML formatter entry point involved in line-length handling; done means the sample formats correctly after adding characters to any of the first three lines, without producing the incorrect mapping-key layout.