MDEV-34466 XA prepare don't release unmodified records for some cases

[vlad-lesin]

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There is no need to exclude exclusive non-gap locks from the procedure
of locks releasing on XA PREPARE execution in
lock_release_on_prepare_try() after commit
17e59ed3aad481918f1a01d8afbc071c316d5930 (MDEV-33454), because
lock_rec_unlock_unmodified() should check if the record was modified
with the XA, and release the lock if it was not.

lock_release_on_prepare_try(): don't skip X-locks, let
lock_rec_unlock_unmodified() to process them.

lock_sec_rec_some_has_impl(): add template parameter for not acquiring
trx_t::mutex for the case if a caller already holds the mutex, don't
crash if lock's bitmap is clean.

row_vers_impl_x_locked(), row_vers_impl_x_locked_low(): add new argument
to skip trx_t::mutex acquiring.

rw_trx_hash_t::validate_element(): don't acquire trx_t::mutex if the
current thread already holds it.

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