contexthub: handle unsupported V4 at top level

Rather than catching and rethrowing in HubInfoRegistry when the HAL
doesn't support the V4 API, defer to a 1-line debug log in
ContextHubService when we get an UnsupportedOperationException from the
HAL.

Bug: 424181658
Test: presubmit
Flag: EXEMPT trivial bugfix
Change-Id: I2361e245364733688129781dac7087d861a6f55a