test_misc.py::test_read_stats fails due to There is no member named _raw.

[tchaikov]

when testing a backport targeting 5.4:

gdb = <module 'gdb' from '/usr/share/gdb/python/gdb/__init__.py'>
sstable = '$sst'

    def test_read_stats(gdb, sstable):
>       scylla(gdb, f'read-stats')

test_misc.py:166: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

gdb = <module 'gdb' from '/usr/share/gdb/python/gdb/__init__.py'>
cmd = 'read-stats'

    def scylla(gdb, cmd):
>       return gdb.execute('scylla ' + cmd, from_tty=False, to_string=True)
E       gdb.error: Error occurred in Python: There is no member named _raw.

test_misc.py:7: error

this backport does not change the memory layout of seastar::lw_shared_ptr or anything related to the schema class.

please note this issue is not reproducible at this moment.

see https://jenkins.scylladb.com/job/scylla-5.4/job/scylla-ci/102/