Problem: pebbledb backend is not tested

[yihuang]

Solution:

• enable the backend and test in integration tests

👮🏻👮🏻👮🏻 !!!! REFERENCE THE PROBLEM YOUR ARE SOLVING IN THE PR TITLE AND DESCRIBE YOUR SOLUTION HERE !!!! DO NOT FORGET !!!! 👮🏻👮🏻👮🏻

PR Checklist:

• Have you read the CONTRIBUTING.md?
• Does your PR follow the C4 patch requirements?
• Have you rebased your work on top of the latest master?
• Have you checked your code compiles? (make)
• Have you included tests for any non-trivial functionality?
• Have you checked your code passes the unit tests? (make test)
• Have you checked your code formatting is correct? (go fmt)
• Have you checked your basic code style is fine? (golangci-lint run)
• If you added any dependencies, have you checked they do not contain any known vulnerabilities? (go list -json -m all | nancy sleuth)
• If your changes affect the client infrastructure, have you run the integration test?
• If your changes affect public APIs, does your PR follow the C4 evolution of public contracts?
• If your code changes public APIs, have you incremented the crate version numbers and documented your changes in the CHANGELOG.md?
• If you are contributing for the first time, please read the agreement in CONTRIBUTING.md now and add a comment to this pull request stating that your PR is in accordance with the Developer's Certificate of Origin.

Thank you for your code, it's appreciated! :)

[codecov]

Codecov Report

Merging #934 (9300e83) into main (7ba584c) will increase coverage by 22.24%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             main     #934       +/-   ##
===========================================
+ Coverage   21.57%   43.81%   +22.24%     
===========================================
  Files          48       62       +14     
  Lines        3004     4838     +1834     
===========================================
+ Hits          648     2120     +1472     
- Misses       2293     2469      +176     
- Partials       63      249      +186     

see 67 files with indirect coverage changes