oe-build-perf-test: simplify stderr log format

Remove timestamps from the stderr log in order to make the console
output more readable, i.e. more in line with the output from unittest
runner.

(From OE-Core rev: d28eeeabde9b4b7160a273445023a44fd50e29ab)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/oe-build-perf-test

@@ -34,8 +34,7 @@ from oeqa.utils.commands import runCmd
 
 
 # Set-up logging
-LOG_FORMAT = '[%(asctime)s] %(levelname)s: %(message)s'
-logging.basicConfig(level=logging.INFO, format=LOG_FORMAT)
+logging.basicConfig(level=logging.INFO, format='%(levelname)s: %(message)s')
 log = logging.getLogger()
 
 
@@ -76,7 +75,7 @@ def setup_file_logging(log_file):
     log_dir = os.path.dirname(log_file)
     if not os.path.exists(log_dir):
         os.makedirs(log_dir)
-    formatter = logging.Formatter(LOG_FORMAT)
+    formatter = logging.Formatter('[%(asctime)s] %(levelname)s: %(message)s')
     handler = logging.FileHandler(log_file)
     handler.setFormatter(formatter)
     log.addHandler(handler)