fix: properly pass headers to client for rejection scenarios (#2059)

Author: DeagleGross

scenarios/rejection.benchmarks.yml

@@ -69,7 +69,7 @@ scenarios:
         connections: 32
         serverScheme: https
         customHeaders:
-        - X-Custom: "Québec"
+        - "X-Custom: Québec"
 
   httpsys-hostheader-mismatch:
     application:
@@ -81,7 +81,7 @@ scenarios:
         connections: 32
         serverScheme: https
         customHeaders:
-        - Host: "google.com"
+        - "Host: google.com"
 
 # Kestrel
 
@@ -106,7 +106,7 @@ scenarios:
         connections: 32
         serverScheme: https
         customHeaders:
-        - X-Custom: "Québec"
+        - "X-Custom: Québec"
 
   kestrel-hostheader-mismatch:
     application:
@@ -118,4 +118,4 @@ scenarios:
         connections: 32
         serverScheme: https
         customHeaders:
-        - Host: "google.com"
+        - "Host: google.com"