More serde snapshot cleanup (backport #22449)

[mergify]

This is an automatic backport of pull request #22449 done by Mergify.
Cherry-pick of 2756abc has failed:

On branch mergify/bp/v1.9/pr-22449
Your branch is up to date with 'origin/v1.9'.

You are currently cherry-picking commit 2756abce3.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   runtime/src/serde_snapshot/storage.rs
	modified:   runtime/src/serde_snapshot/tests.rs
	modified:   runtime/src/snapshot_utils.rs

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   runtime/src/serde_snapshot.rs
	both modified:   runtime/src/serde_snapshot/newer.rs

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

---

Mergify commands and options

More conditions and actions can be found in the documentation.

You can also trigger Mergify actions by commenting on this pull request:

• @Mergifyio refresh will re-evaluate the rules
• @Mergifyio rebase will rebase this PR on its base branch
• @Mergifyio update will merge the base branch into this PR
• @Mergifyio backport <destination> will backport this PR on <destination> branch

Additionally, on Mergify dashboard you can:

• look at your merge queues
• generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com

[mergify]

automerge label removed due to a CI failure

[codecov]

Codecov Report

Merging #22872 (bbc1794) into v1.9 (3aa3cd8) will decrease coverage by 0.0%.
The diff coverage is 56.9%.

@@            Coverage Diff            @@
##             v1.9   #22872     +/-   ##
=========================================
- Coverage    81.2%    81.1%   -0.1%     
=========================================
  Files         530      531      +1     
  Lines      146864   146866      +2     
=========================================
- Hits       119283   119246     -37     
- Misses      27581    27620     +39     

[github-actions]

This PR has been automatically locked since there has not been any activity in past 14 days after it was merged.