MDEV-34529  Shrink the system tablespace when system tablespace contains MDEV-30671 leaked undo pages

- InnoDB fails to shrink the system tablespace when it contains
the leaked undo log pages caused by MDEV-30671.

- InnoDB does free the unused segment in system tablespace
before shrinking the tablespace.

inode_info: Structure to store the inode page and offsets.

fil_space_t::garbage_collect(): Frees the system tablespace
unused segment

fsp_free_unused_seg(): Frees the unused segment

fsp_get_sys_used_segment(): Iterates through all default
file segment and index segment present in system tablespace.

fseg_inode_free(): Frees the extents, fragment pages for the
given index node and ignores any error similar to
trx_purge_free_segment()

trx_sys_t::reset_page(): Retain the TRX_SYS_FSEG_HEADER value
in trx_sys page while resetting the page.