DAOS-19086 cart: Change hg address cache key to combine rank and tag

[frostedcmos]

HG Addr caching changes in cart:

• Instead of keeping array of all tags per rank, combine rank and tag into a single key and use it to identify needed hg_addr

Steps for the author:

• Commit message follows the guidelines.
• Appropriate Features or Test-tag pragmas were used.
• Appropriate Functional Test Stages were run.
• At least two positive code reviews including at least one code owner from each category referenced in the PR.
• Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions]

Ticket title is 'cart: Change hg address cache key to combine rank and tag'
Status is 'Open'
Labels: 'multipath'
https://daosio.atlassian.net/browse/DAOS-19086

[soumagne]

didn't really spend too much time reviewing it but it seems good I think...

[daosbuild3]

Test stage Functional Hardware Medium MD on SSD completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18453/1/testReport/