The `agent_profile_switched` event fired from the profile picker was
using snake_case instead of the title case used by every other agent
telemetry event. This caused it to land in Amplitude as a separate event
from the `Agent Profile Switched` event fired by keyboard cycling,
making it impossible to track profile switches in a single chart.

Renames the event to `Agent Profile Switched` to match. The `source`
property (`"picker"` vs `"cycle"`) still distinguishes the two code
paths.

Release Notes:

- N/A