MDEV-34733 main.mysqld--help-aria test failure: feedback plugin: failed to retrieve the MAC address

* replace the message away in the test result
* remove "feedback plugin:" prefix, it's a server message, not plugin's
* downgrade to the warning, because
   1) it's not a failure, no operation was aborted, server still works
   2) it's something actionable, so not a [Note] either

mysql-test/main/mysqld--help-aria.test

@@ -6,7 +6,7 @@ flush tables;
 --let $args=--table-cache=5 --max-connections=10 --log-warnings=1 --silent-startup --lower-case-table-names=1 --help --verbose
 
 --exec $MYSQLD_CMD $args > $MYSQL_TMP_DIR/mysqld--help2.txt 2> $MYSQL_TMP_DIR/mysqld--help2.err
---replace_regex /mysqld/mariadbd/ /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* //
+--replace_regex /mysqld/mariadbd/ /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* // /^.*failed to retrieve the MAC address\n//
 --cat_file $MYSQL_TMP_DIR/mysqld--help2.err
 
 --echo #
@@ -14,7 +14,7 @@ flush tables;
 --echo #
 
 --exec $MYSQLD_CMD $args --datadir=$MYSQL_TMP_DIR/help > $MYSQL_TMP_DIR/mysqld--help2.txt 2> $MYSQL_TMP_DIR/mysqld--help2.err
---replace_regex /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* //
+--replace_regex /mysqld/mariadbd/ /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* // /^.*failed to retrieve the MAC address\n//
 --cat_file $MYSQL_TMP_DIR/mysqld--help2.err
 
 --echo #
@@ -23,7 +23,7 @@ flush tables;
 
 --mkdir $MYSQL_TMP_DIR/help
 --exec $MYSQLD_CMD $args --datadir=$MYSQL_TMP_DIR/help > $MYSQL_TMP_DIR/mysqld--help2.txt 2> $MYSQL_TMP_DIR/mysqld--help2.err
---replace_regex /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* //
+--replace_regex /mysqld/mariadbd/ /\d\d\d\d-\d*-\d* *\d*:\d*:\d* \d* // /^.*failed to retrieve the MAC address\n//
 --cat_file $MYSQL_TMP_DIR/mysqld--help2.err
 --list_files $MYSQL_TMP_DIR/help
 

mysql-test/mysql-test-run.pl

@@ -4487,7 +4487,7 @@ sub extract_warning_lines ($$) {
      qr|InnoDB: io_setup\(\) failed with EAGAIN|,
      qr/InnoDB: Failed to set (O_DIRECT|DIRECTIO_ON) on file/,
      qr|setrlimit could not change the size of core files to 'infinity';|,
-     qr|feedback plugin: failed to retrieve the MAC address|,
+     qr|failed to retrieve the MAC address|,
      qr|Plugin 'FEEDBACK' init function returned error|,
      qr|Plugin 'FEEDBACK' registration as a INFORMATION SCHEMA failed|,
      qr|'log-bin-use-v1-row-events' is MySQL .* compatible option|,

sql/mysqld.cc

@@ -9866,7 +9866,7 @@ static int calculate_server_uid(char *dest)
   int2store(rawbuf, mysqld_port);
   if (my_gethwaddr(rawbuf + 2))
   {
-    sql_print_error("feedback plugin: failed to retrieve the MAC address");
+    sql_print_warning("failed to retrieve the MAC address");
     return 1;
   }