1. Slice of fix for Bug#42003 tests missing the disconnect of connections <> default

- If missing: add "disconnect <session>"
   - If physical disconnect of non "default" sessions is not finished
     at test end: add routine which waits till this happened
+ additional improvements like
  - remove superfluous files created by the test
  - replace error numbers by error names
  - remove trailing spaces, replace tabs by spaces
  - unify writing of bugs within comments
  - correct comments
  - minor changes of formatting
Modifications according to the code review are included.
Fixed tests:
grant2
grant3
lock_tables_lost_commit
mysqldump
openssl_1
outfile

mysql-test/include/count_sessions.inc

@@ -0,0 +1,21 @@
+# include/count_sessions.inc
+#
+# SUMMARY
+#
+#    Stores the number of current sessions in $count_sessions.
+#
+#
+# USAGE
+#
+#    Please look into include/wait_until_count_sessions.inc
+#    for examples of typical usage.
+#
+#
+# EXAMPLE
+#    backup.test, grant3.test
+#
+#
+# Created: 2009-01-14 mleich
+#
+
+let $count_sessions= query_get_value(SHOW STATUS LIKE 'Threads_connected', Value, 1);