Add a new table-level configuration option to override the connection level tiered shared option to disable/enable the tiered shared for a particular table.

Config(shared, 'true', r''' 
enable sharing the tiered table across other WiredTiger instances.''', type='boolean'),

This option will override the connection level tiered shared option. If the connection level tiered shared option is disabled, enabling it via table level will simply ignore it with a warning message.