fix(auth): stop reporting Block Store calls Play services doesn't support

[bmc08gt]

Bugsnag error 6abc0c6b991833fd09b525ad is an UnsupportedApiCallException for blockstore_retrieve_bytes_with_options v3. It comes from devices whose Play services is too old for retrieveBytes(RetrieveBytesRequest): 10 events from 3 users so far, on older vivo and realme phones running Android 11 and 12.

PlayBlockStoreBytes already catches the failure and returns null, which the class documents as the intended fallback. The noise comes from trace(error = ...), which forwards any error to Bugsnag.notify. Launch reads Block Store more than once, so each launch filed 2–3 warnings.

Read, write and delete now go through traceFailure, which logs UnsupportedApiCallException as a breadcrumb and keeps reporting everything else. Return values are unchanged.

After the first UnsupportedApiCallException from a read, later reads in the same process return null without calling Play services. There's no reliable check up front: checkApiAvailability passes because the Block Store API itself exists, and the error reports is_fully_rolled_out=false, so a Play services version gate would misjudge devices too. Writes and deletes use different features, and nothing shows them failing, so they still call through.

Every failure path now calls ensureActive() before handling the error, because runCatching was also catching coroutine cancellation. The write path is where this mattered most: a cancel during the isEndToEndEncryptionAvailable check fell back to false and went on to issue storeBytes with cloud backup off, which deletes the existing cloud copy on the next sync. ensureActive() throws only when the calling coroutine is cancelled, so a Play services task that fails with its own CancellationException is still treated as a failure.

There's no unit test: the class talks to Play services directly, and the existing tests use a fake behind BlockStoreBytes.