LocalBuildConfiguration: log to <build_dir>/build.log not <build_dir>/build-2.log

Since the build log is already within the a build-specific directory, we
don't need to put the build ID (which ends up always being "2") into the
build log filename.

module_build_service/common/config.py

@@ -79,6 +79,7 @@ class LocalBuildConfiguration(BaseConfiguration):
     CACHE_DIR = "~/modulebuild/cache"
     LOG_LEVEL = "debug"
     MESSAGING = "drop"
+    BUILD_LOGS_NAME_FORMAT = "build.log"
 
     ALLOW_CUSTOM_SCMURLS = True
     RESOLVER = "mbs"