DAOS-15810 control: Rework daos_agent AttachInfo handling

[mjmac]

Reduce some gc pressure under heavy load by avoiding type conversions between protobuf and native Go types for the AttachInfo data.

Also avoid deep copies in favor of creating new structs as necessary to perform per-client customizations. The new structs refer to members in the original struct, which is thread-safe because the original struct's fields are only ever read, never written.

Features: control Required-githooks: true Change-Id: I738f8c2d8cfac865cb20962f0aa1e70327649b2d Signed-off-by: Michael MacDonald [email protected]

[github-actions[bot]]

Ticket title is 'Agent crashes with concurrent pool connect via slurm' Status is 'Open' Labels: 'triaged' https://daosio.atlassian.net/browse/DAOS-15810

[daosbuild1]

Test stage Functional Hardware Medium Verbs Provider completed with status FAILURE. https://build.hpdd.intel.com//job/daos-stack/job/daos/view/change-requests/job/PR-14337/2/execution/node/1455/log

[mjmac]

The hw-medium-verbs failure appears to be a typical rebuild suite timeout. This PR doesn't change anything having to do with rebuild or pools. Waiting for feedback from @johannlombardi on whether or not the approach in this PR seems to help with the problem he is seeing.