runtests: allow comments in setenv section, merge sections in test433

[vszakats]

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Comments were silently allowed before this patch, but internally they
were handled as env deletion commands, which just failed or did not
do harm. I figure it's better to allow explicitly and not pass to OS.

[Copilot]

Pull request overview

Updates the curl test runner to support comment lines inside <setenv> sections in test definitions, and simplifies test433 by consolidating its environment setup into a single <setenv> block.

Changes:

• Teach tests/runner.pm to ignore #... comment lines when processing <setenv>.
• Merge the duplicated <setenv> sections in tests/data/test433 and keep the explanatory note as an inline comment.
• Keep the COLUMNS=300 adjustment within the main env block to avoid word-wrapped output during the test.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
tests/runner.pm	Skips # comment lines while parsing <setenv> entries so comments don’t get treated as environment variable names.
tests/data/test433	Consolidates env setup into one <setenv> section and adds an inline comment for the COLUMNS override.

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[vszakats]

It appears we have an upstream CI meltdown.