storage: make Azure blobID chunk delimiter configurable

[tatchiuleung]

What this PR does / why we need it:
Make the - chunk delimiter configurable, instead of hardcoded one -.

Which issue(s) this PR fixes:
Fixes #5712

Special notes for your reviewer:
@dannykopping @khaines I would appreciate if you can review it. Thank you!

Checklist

• Documentation added
• Tests updated
• Add an entry in the CHANGELOG.md about the changes.

[CLAassistant]

All committers have signed the CLA.

[tatchiuleung]

@ronyrv13 Feel free to add or change anything in this PR.

[ronyrv13]

Hello @tatchiuleung

I have tested loki with this PR changes, and it really worked.
I am able to pull the old logs & new logs with chunk_delimiter config set to ":" with azure storage config.

You can find few SS below-

Old Logs Chunks which was successfully fetched -

chunk_delimiter config set to "-"

Latest logs also Fetched successfully-

cc: @dannykopping

[ronyrv13]

Loki Config Used-

    storage_config:
        azure:
          container_name: ${CONTAINER_NAME}
          account_name: ${STORAGE_ACCOUNT_NAME}
          account_key: ${STORAGE_ACCOUNT_KEY}
          chunk_delimiter: ":"
        boltdb_shipper:
            shared_store: azure
        index_queries_cache_config:

[tatchiuleung]

@ronyrv13 Thank you for the test!

[sandeepsukhani]

LGTM

[sandeepsukhani]

Thanks for the PR! Can you please resolve conflicts with changelog so that I can merge this?

[tatchiuleung]

@sandeepsukhani Done!

[dannykopping]

Apologies for not reviewing this PR - I was on vacation this week.
This PR is exactly why I love open-source... You found an issue, reported it, posted a PR to fix, and made the product better ❤️

Thanks a lot!

[prasadrajesh]

Thanks @tatchiuleung and @ronyrv13 for contribution to make working chunk_delimiter: ":".