[YAML] Parse mappings with keys containing # characters

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11700
| License       | MIT
| Doc PR        | 
yeah, I think this catch statement is a left-over from before we introduced ParseException in the component