[3.0] Restore the blank line the section banners want around them

[albertlast]

Note

This change was produced by an LLM. The change, the commit message and this
description were all written by Claude (Anthropic), driven by @albertlast.

Description

Three files in release-3.0 do not match what the custom SMF/section_comments
fixer produces. Sources/Alert.php is missing the blank line before a banner;
Sources/Autolinker.php and Sources/Actions/Help.php each carry an extra one.
Three lines in total, and composer lint-fix writes all of it.

The interesting part is why nobody noticed.

.github/workflows/php-cs-fixer.yml asks tj-actions/changed-files what the pull
request touched and then, on line 24:

if ! echo "${CHANGED_FILES}" | grep -qE "^(\.php-cs-fixer(\.dist)?\.php|composer\.lock)$"; then
    EXTRA_ARGS=$(printf -- '--path-mode=intersection\n--\n%s' "${CHANGED_FILES}")
fi

So unless the pull request changes the fixer's own config or composer.lock, the
check only ever looks at the files that pull request touched. That is the right
call for speed, and it means a file can drift out of compliance and stay there
indefinitely: nothing re-checks it until somebody edits it again, or until a branch
comes along that does change one of those two files and turns the check back into a
whole-tree scan.

That is how these turned up. #9511 changes composer.lock, so its check ran over
all 1738 files and reported these three, none of which that branch goes anywhere
near.

How this was verified

• vendor/bin/php-cs-fixer check --allow-risky=yes over the whole tree:
  Found 0 of 1684 files that can be fixed, against 3 before this change.
• The three files are otherwise untouched — the entire diff is one blank line added
  and two removed.
• check-signed-off.php passes locally.

Relationship to other PRs

Independent, and worth merging on its own. #9511 and #9326 both change
composer.lock and so both get the whole-tree scan; they stay red on these three
files until this lands.

Issues References (Fixes|Related|Closes)

1. Related: [3.0][Testing] Cover last week's fixes that the unit suite can reach #9511, [3.0][Testing] Add a PHPUnit suite for the parts that need no database #9326