Due to 32-bit arithmetics, SRV_TMP_SPACE_ID page number 0x200002 would be
folded to 0, which is incompatible with the assumption that was made in
commit 7cffb5f6 (MDEV-23399).

page_id_t::fold(): Compute in the native word width instead of uint32_t.
On 64-bit platforms, an alternative would be to return the 64-bit m_id
directly, but that was measured to cause a performance regression.

fil_space_t::open(): Invoke fil_node_t::find_metadata() when the
tablespace is being created. In this way, we will actually detect
that the temporary tablespace resides on SSD. (During database
creation, also the system tablespace will correctly be detected as
residing on SSD.)