fix: ensure reactions are kept dirty when marking them again

[dummdidumm]

previously a reaction could be marked as DIRTY and subsequently as MAYBE_DIRTY before running, resulting in false negatives. Ensure that DIRTY flag can never be lowered to MAYBE_DIRTY
fixes #11363
fixes #11352
fixes #11368

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• Prefix your PR title with feat:, fix:, chore:, or docs:.
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint

[changeset-bot]

🦋 Changeset detected

Latest commit: 94ad6ce

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
svelte	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[paoloricciuti]

Uh i guess this could be the reason my #11290 has a failing test...will try to run it again after this is merged.

[MotionlessTrain]

I have the feeling that this may also fix #11352

[dummdidumm]

Indeed it does, thanks for flagging!