When initializing streaming sources in tablet_stream_files_handler we
use a reference to the table. We should hold the table while doing so,
because otherwise the table may be dropped and destroyed when we yield.
Use the table.stream_in_progress() phaser to hold the table while we
access it.
For sstable file streaming we can release the table after the snapshot
is initialized, and the table may be dropped safely because the files
are held by the snapshot and we don't access the table anymore. There
was a single access to the table for logging but it is replaced by a
pre-calculated variable.
For logstor segment streaming, currently it doesn't support discarding
the segments while they are streamed - when the table is dropped it
discard the segments by overwriting and freeing them, so they shouldn't
be accessed after that. Therefore, in that case continue to hold the
table until streaming is completed.
Fixes [SCYLLADB-1533](https://scylladb.atlassian.net/browse/SCYLLADB-1533)
It's a pre-existing use-after-free issue in sstable file streaming so should be backported to all releases.
It's also made worse with the recent changes of logstor, and affects also non-logstor tables, so the logstor fixes should be in the same release (2026.2).
[SCYLLADB-1533]: https://scylladb.atlassian.net/browse/SCYLLADB-1533?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQClosesscylladb/scylladb#29488
* github.com:scylladb/scylladb:
test: test drop table during streaming
streaming: stream_blob: hold table for streaming
9bfcc25cf7