fix for dup digest smashing in cosign

[amartin120]

Please check below, if the PR fulfills these requirements:

• Commit(s) and code follow the repositories guidelines.
• Test(s) have been added or updated to support these change(s).
• Doc(s) have been added or updated to support these change(s).

Associated Links:

Types of Changes:

• Bugfix. Shared digests are getting smashed in the index.json due to a change made in our cosign fork for the last release. I've reverted that change in a new tag v2.2.3+carbide.2.

Proposed Changes:

• Reverted change in our cosign fork that was put into place to keep duplicates out of the index.json if you ran the image add command twice but that didn't jive well when 2 different images shared layers. Sticking with the lesser of the 2 evils.

Verification/Testing of Changes:

• Tested with the longhorn and mirrored-longhorn images. (Thanks Brian Durden)

Additional Context:

• specific cosign change - hauler-dev/cosign@4954236

[dweomer]

LGTM (this sounds fun, and by bun i mean the opposite of such)