Fixtures previously ran GDB once (module scope) to find live objects
(sstables, tasks, schemas) and stored their addresses. Tests then
reused those addresses in separate GDB invocations. Sometimes these
addresses would become stale and the test would step on use-after-free
(e.g. sstables compacted away between invocations).
Fix by dropping the fixtures. The helper functions used by the fixtures
to obtain the required objects are converted to gdb convenience
functions, which can be used in the same expression as the test command
invocation. Thus, the object is aquired on-demand at the moment it is
used, so it is guaranteed to be fresh and relevant.
Fixes: SCYLLADB-1020
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Closesscylladb/scylladb#28999
772b32d9f7