Remove intermediate variables for conversion start/end logs

Also, state that the logs are incomplete in the header.

dangerzone/isolation_provider/base.py

@@ -20,9 +20,6 @@
 
 log = logging.getLogger(__name__)
 
-DOC_TO_PIXELS_LOG_START = "----- DOC TO PIXELS LOG START -----"
-DOC_TO_PIXELS_LOG_END = "----- DOC TO PIXELS LOG END -----"
-
 TIMEOUT_EXCEPTION = 15
 TIMEOUT_GRACE = 15
 TIMEOUT_FORCE = 5
@@ -359,14 +356,13 @@ def doc_to_pixels_proc(
                 debug_bytes = stderr.getvalue()
                 debug_log = sanitize_debug_text(debug_bytes)
 
-                incomplete = "(incomplete)\n" if stderr_thread.is_alive() else ""
+                incomplete = "(incomplete) " if stderr_thread.is_alive() else ""
 
                 log.info(
                     "Conversion output (doc to pixels)\n"
-                    f"{DOC_TO_PIXELS_LOG_START}\n"
+                    f"----- DOC TO PIXELS LOG START ${incomplete}-----\n"
                     f"{debug_log}"  # no need for an extra newline here
-                    f"{incomplete}"
-                    f"{DOC_TO_PIXELS_LOG_END}"
+                    "----- DOC TO PIXELS LOG END -----"
                 )
 
     def start_stderr_thread(