TDC_RT_REMOVE_ALL -> tdc_remove_table(). Some occurrences replaced with
TDC_element::flush() (whenver TABLE_SHARE is available).

TDC_RT_REMOVE_NOT_OWN[_KEEP_SHARE] -> TDC_element::flush(). These modes
assume that current thread owns TABLE_SHARE reference, which means we can
avoid hash lookup and flush unused TABLE instances directly.

TDC_RT_REMOVE_UNUSED -> TDC_element::flush_unused(). Only [ab]used by
mysql_admin_table() currently. Should be removed eventually.

Part of MDEV-17882 - Cleanup refresh version