util/abuild: Delete temporary config in failure case

Change-Id: I9b6e6b6dcfbf2b1f43c98027acae8d9af61bd6d8
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/44624
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/abuild/abuild

@@ -852,6 +852,7 @@ build_targets()
 		junit "</failure>"
 		junit "</testcase>"
 		echo "Shared Utilities - Log: $TARGET/sharedutils/make.log" >> "$FAILED_BOARDS"
+		rm "$TMPCFG"
 		return
 	fi