[HttpFoundation] [Tests] fix typo in Memcached tests skipped message

| Q             | A
| ------------- | ---
| Typo fix | yes
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT
| Fixed tickets | -
| Doc PR        | -