MDEV-37862 - innodb.gap_locks test failure: 0 lock structs, 0 row locks

Test was affected by incompletely closed preceding connections.

Make test agnostic to concurrent connections by querying
InnoDB status only for connections that it uses.

This is an addition to 3b2169f, which didn't handle a case when
preceding test has active transaction on disconnect.

Author: svoj

mysql-test/suite/innodb/t/gap_locks.test

@@ -6,6 +6,8 @@ INSERT INTO t1 VALUES (1,'1',1),(2,'2',1);
 
 SET @save_locks= @@GLOBAL.innodb_status_output_locks;
 SET GLOBAL INNODB_STATUS_OUTPUT_LOCKS = 'ON';
+let $default_id= `select connection_id()`;
+let $reg= /.*---TRANSACTION \d+, ACTIVE.*?(\d+ lock struct...), heap size \d+(, \d+ row lock...).*?\nMariaDB thread id $default_id,.*/\1\2/;
 
 let $isolation= 4;
 while ($isolation) {
@@ -34,7 +36,7 @@ DELETE FROM t1 WHERE b='2' AND c=2;
 # not of any inactive ones. Note the use of non-greedy match ".*?", so that
 # we get the values for the ACTIVE transaction, not the last values in the
 # list.
---replace_regex /.*---TRANSACTION \d+, ACTIVE.*?(\d+ lock struct...), heap size \d+(, \d+ row lock...).*/\1\2/
+--replace_regex $reg
 SHOW ENGINE INNODB STATUS;
 ROLLBACK;