Tests: remove unused function.

This function was accidentally added in e0f0cd7d244a.

test/unit.py

@@ -2,7 +2,6 @@ import os
 import re
 import sys
 import json
-import mmap
 import time
 import shutil
 import socket
@@ -367,11 +366,6 @@ class TestUnitApplicationProto(TestUnitControl):
         with open(self.testdir + '/unit.log', 'r', errors='ignore') as f:
             return re.search(pattern, f.read())
 
-    def find_in_log(self, pattern):
-        with open(self.testdir + '/unit.log', 'rb', 0) as f, \
-             mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as s:
-            return s.find(pattern) != -1
-
 class TestUnitApplicationPython(TestUnitApplicationProto):
     def load(self, script, name=None):
         if name is None: