Adjust test since ProcessPartial no more causes "no final boundary missing"

Due to the previous change, the "no final boundary missing" error never
occurs when SecRequestBodyLimitAction is ProcessPartial.

Author: hnakamur

tests/regression/config/10-request-directives.t

@@ -578,10 +578,10 @@
 		SecRequestBodyLimit 131072
 	),
 	match_log => {
-		error => [ qr/Multipart parsing error: Multipart: Final boundary missing./, 1],
+		-error => [ qr/Multipart parsing error: Multipart: Final boundary missing./, 1],
 	},
 	match_response => {
-		status => qr/^500$/,
+		status => qr/^200$/,
 	},
 	request => normalize_raw_request_data(
 		qq(