ci(android): Bump Maestro to 2.7.0 for UI critical tests (#5798)

Update the pinned Maestro CLI version used by the UI critical
integration tests from 2.1.0 to the latest 2.7.0. No flow changes
are required; all commands used remain supported and the Java 17
requirement is already satisfied by the CI job.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>