Fixes docdb unit test

[PuneetPunamiya]

Changes

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• [ ] Has Docs included if any changes are user facing
• [ ] Has Tests included if any functionality added or changed
• [ ] Follows the commit message standard
• [ ] Meets the Tekton contributor standards (including functionality, content, code)
• [ ] Release notes block below has been updated with any user facing changes (API changes, bug fixes, changes requiring upgrade notices or deprecation warnings)
• [ ] Release notes contains the string "action required" if the change requires additional action from users switching to the new release

Release Notes

NONE

[tekton-robot]

The following is the coverage report on the affected files. Say /test pull-tekton-chains-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/chains/storage/docdb/docdb.go	76.0%	74.4%	-1.7

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lcarva

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