PT-2168 pt-osc shouldnt fail while unable to monitor a replica node (#676)

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Proof of concept
- Fixed regular expression in lib/TableParser.pm mistakenly chaged in the tool's code

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Added basic test case for PT-2168
- Added more details for replica lag information
- Disconnecting replica if lag is not checked. This prevents "Too many
  connections" error

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Implemented option --wait-lost-replicas for pt-osc, added test case

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Added more tests for situations where connection to the replica can
  fail

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Removed extra checks for wait_no_die variable
- Added test cases for SQL queries that pt-osc sends to replicas

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Allow to reload dsns table while waiting for missed replica if
  --recursion-method is dsn
- Fixed logic in replica rediscovery, so it works with replicas on the
  same host but with different ports
- Renamed option wait-lost-replicas to fail-on-stopped-replication, so
  it is in line with pt-table-checksum
- Adjusted tests
- Removed debug code for PT-1760
- Added test case for PT-1760
- Added exception for variable Open_tables_with_triggers in
  lib/bash/collect.sh due to failed test in Percona Server 8.0.34+
- Updated pt-stalk

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Updated modules
- Fixed typo in t/pt-table-sync/bidirectional.t
- Removed trailing whitespaces in lib/MasterSlave.pm

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Help for option --fail-on-stopped-replication

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Added check for availability of the simple_rewrite_plugin in t/pt-online-schema-change/pt-2168.t

* PT-2168 - PT-OSC shouldn't fail while unable to monitor a replica node

- Added link to the simple_rewrite_plugin source code
- Removed tests for code that runs only in the beginning of pt-osc
  action, so should not be affected by the option fail-on-stopped-replication

lib/bash/collect.sh

@@ -392,7 +392,7 @@ collect_mysql_data_two() {
 }
 
 open_tables() {
-   local open_tables=$($CMD_MYSQLADMIN $EXT_ARGV ext | grep "Open_tables" | awk '{print $4}')
+   local open_tables=$($CMD_MYSQLADMIN $EXT_ARGV ext | grep "Open_tables" | grep -v "Open_tables_with_triggers" | awk '{print $4}')
    if [ -n "$open_tables" -a $open_tables -le 1000 ]; then
       $CMD_MYSQL $EXT_ARGV -e 'SHOW OPEN TABLES' &
    else