Increased  the number of rows in AbuseFilter's Filter testing textarea

The text areas for the table row had only 5 rows, which is a lot less than
 the default number of rows.So now the number of rows in the testing textarea is changed to 15.

Bug: 59869
Change-Id: I9f221e7a49473ae1d473333f7ecf26235366d257
Merge "Increased  the number of rows in AbuseFilter's Filter testing textarea"