Remove dead bindings from the agent sessions index

What does this MR do and why?

Removes two dead bindings from ee/app/assets/javascripts/ai/duo_agents_platform/pages/index/duo_agents_platform_index.vue. One file, three deletions, no behaviour change.

1. The emptyStateIllustrationPath import and its $options static entry.
2. The :initial-sort="initialSort" binding on <agent-flow-list>.

Both were dead on arrival. The index did once consume the illustration: it had inject: ['emptyStateIllustrationPath', 'isSidePanelView'] and passed it down as :empty-state-illustration-path. Commit d4afdbe2 (2025-09-18, "Add project info to Sessions") deleted both and moved the import inside agent_flow_list.vue, where it still lives. The import being removed here is not that earlier consumer — it landed a day later in d3305960 (2025-09-19, "Added integration of duo side-rail"), was reverted the same day in 1b1b1d59, and relanded in 1239ac19 (2025-09-23). git log -S'gl-empty-state' and git log -S'svg-path' on the index file return nothing across its entire history, so the index has never rendered an empty state of its own and the import has never been read.

The :initial-sort binding on <agent-flow-list> was added in 6799e019 (2025-10-10, "Feat: add search to agent sessions"), the change that introduced sorting. git log -S'initialSort' on agent_flow_list.vue is empty across all history: that component has never declared an initialSort prop, so the binding has been falling through as a plain DOM attribute since the day it was written. The sibling :initial-sort on <agent-flow-filtered-search> is the live one and is untouched.

The initialSort prop on the index itself and its binding on <agent-flow-filtered-search> are live and untouched. No spec changes are needed — git grep confirms no spec asserts either deleted binding, and the existing index spec passes unmodified.

This is groundwork for #616493 (closed), which adds a new panel component modelled on this file. Removing the dead bindings first stops them from being copied.

References

• Issue: #616493 (closed)
• Parent epic: gitlab-org#23179 (closed)
• Related MR (target branch source): !250654 (merged)

This MR targets the branch 616492-extract-agent-flow-filtered-search rather than master because !250654 (merged) rewrites the same import block; a master-based version of this cleanup would conflict with it. Retarget to master once that MR merges.

Screenshots or screen recordings

No visual change.

How to set up and validate locally

Open the Duo panel or the Sessions page and confirm the list, its empty state, and sorting all behave as before. There is nothing new to see.

Automated verification: yarn jest ee/spec/frontend/ai/duo_agents_platform/pages/index/duo_agents_platform_index_spec.js passes, and yarn lint:eslint is clean on the file.

MR acceptance checklist

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