minor #21461 [HttpFoundation] Mark more methods as @final (nicolas-…

…grekas)

This PR was merged into the 3.3-dev branch.

Discussion
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[HttpFoundation] Mark more methods as `@final`

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

Follow up of #19734 (ping @GuilhemN)

Commits
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84a664f [HttpFoundation] Mark more methods as `@final`