MDEV-14606 Assertion failure on IMPORT TABLESPACE

fseg_alloc_free_page_low(): Remove a bogus and redundant assertion about
fil_space_t::purpose. The debug function fsp_space_modify_check()
is asserting something similar, but more accurately.

storage/innobase/fsp/fsp0fsp.cc

@@ -2446,8 +2446,6 @@ fseg_alloc_free_page_low(
 	ut_ad(mach_read_from_4(seg_inode + FSEG_MAGIC_N)
 	      == FSEG_MAGIC_N_VALUE);
 	ut_ad(!((page_offset(seg_inode) - FSEG_ARR_OFFSET) % FSEG_INODE_SIZE));
-	ut_ad(space->purpose == FIL_TYPE_TEMPORARY
-	      || space->purpose == FIL_TYPE_TABLESPACE);
 	seg_id = mach_read_from_8(seg_inode + FSEG_ID);
 
 	ut_ad(seg_id);