test: fix flakiness in test Needed for # 6128 NO_CHANGELOG=fix test NO_DOC=fix test

test: fix flakiness in gh_6128_background_mode_test Test runs an external process with tarantool that writes to a log file. Then test reads that log file and searches a string with required message in it (see function check_err_msg). Test was flaky on macOS and I suspect it was happening due to a high log level - timeout was not enough to wait message in the log file. Patch decreases a log level to a default value and replaces io functions with the similar alternatives in a fio module. Using fio functions allows to not block fibers. NO_CHANGELOG=test fix NO_DOC=test fix

lua/xlog: don't ignore unknown header fields The xlog reader Lua module uses the xlog_cursor_next_row, which decodes the row header with xrow_header_decode. The latter silently ignores any unknown fields, which complicates catching bugs when garbage is written to a row header by mistake, for example, see #8783. Let's parse a row header without using xrow_header_decode in the xlog reader module, like we parse a row body, and output all unknown/invalid keys as is. To do that, we have to extend the xlog cursor API with the new method xlog_cursor_next_row_raw that returns a pointer to the position in the tx buffer where the next xrow is stored without advancing it. To avoid a memory leak in case the caller fails to parse an xrow returned by this function, we also have to move the call to xlog_tx_cursor_destroy from xlog_tx_cursor_next_row to xlog_cursor_next_tx. While we are at it, - Don't raise an error if a key type encountered in a row body is invalid (not an integer). Instead, silently ignore such keys. - Remove the useless body MsgPack validness check because we already check it after decoding the header. - Add error injection based tests to check all the corner cases. NO_DOC=bug fix

txn: reset stream_id row header field To avoid garbage written to xlog. Closes #8783 NO_DOC=bug fix NO_TEST=next commit

update: add tests related to multiple update to the same field These are misc tests that can be related to the issue. Not sure all of them do not work before the patch set for the issue. It is nice to have them and be sure everything works fine. Closes #8658 NO_DOC=minor