test: cover metro session runtime flows [WPB-25946]

[Garzas]

https://wearezeta.atlassian.net/browse/WPB-25946

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What's new in this PR?

Adds regression coverage for the Metro session runtime flows that were breaking during the Hilt to Metro migration.

The tests cover:

• login path that reaches the too-many-devices flow,
• cancelling/removing a device from the too-many-devices screen,
• returning from add-account login back to an existing session,
• logout/session transition behavior,
• removed-client event handling when another account is available,
• removed-client event handling when no other account is available.

Why

These scenarios caught the recent runtime regressions around session-scoped Metro graphs, account switching, logout, and client removal. Keeping them covered should make the remaining Metro migration safer and prevent us from reintroducing white screens, stale session graphs, or wrong-account state.

Validation

• Added critical-flow style UI test coverage for the session/account edge cases.
• Branch is stacked on top of fix/metro-session-runtime-stability.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[MohamadJaara]

can you please add it to regression tests please instead of critical flow or sync with @emmaoke-w if it must be in critical?

[pull-request-size]

Ups 🫰🟨

This PR is too big. Please try to break it up into smaller PRs.