Problem appears to be that the function fsp_flags_try_adjust()
is being unconditionally invoked on every .ibd file on startup.
Based on performance investigation also the top function
fsp_header_get_crypt_offset() needs to addressed.

Ported implementation of fsp_header_get_encryption_offset()
function from 10.2 to fsp_header_get_crypt_offset().

Introduced a new function fil_crypt_read_crypt_data()
to read page 0 if it is not yet read.

fil_crypt_find_space_to_rotate(): Now that page 0 for every .ibd
file is not read on startup we need to check has page 0 read
from space that we investigate for key rotation, if it is not read
we read it.

fil_space_crypt_get_status(): Now that page 0 for every .ibd
file is not read on startup here also we need to read page 0
if it is not yet read it. This is needed
as tests use IS query to wait until background encryption
or decryption has finished and this function is used to
produce results.

fil_crypt_thread(): Add is_stopping condition for tablespace
so that we do not rotate pages if usage of tablespace should
be stopped. This was needed for failure seen on regression
testing.

fil_space_create: Remove page_0_crypt_read and extra
unnecessary info output.

fil_open_single_table_tablespace(): We call fsp_flags_try_adjust
only when when no errors has happened and server was not started
on read only mode and tablespace validation was requested or
flags contain other table options except low order bits to
FSP_FLAGS_POS_PAGE_SSIZE position.

fil_space_t::page_0_crypt_read removed.

Added test case innodb-first-page-read to test startup when
encryption is on and when encryption is off to check that not
for all tables page 0 is read on startup.