[REV-1606] Hide empty other members usage row

[IsaiahWitzke]

Description

Fixes the billing v2 member usage predicate so zero-value Team aggregate entries do not count as other-member data. This hides the stray "Other members" row for solo workspaces while still showing it when historical aggregate usage exists for other members.

Linked Issue

REV-1606

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below (especially for user-visible or UI changes).

Testing

• cargo fmt --check

• cargo test -p warp has_non_viewer_data --lib

• cargo clippy -p warp --lib -- -D warnings

• I have manually tested my changes locally with ./script/run

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

CHANGELOG-BUG-FIX: Hide the empty "Other members" row on the billing and usage page for solo teams.

This PR was created by Oz (running Codex).

[IsaiahWitzke]

superseded by https://github.com/warpdotdev/warp/pull/11434/changes#r3290819885