No need to fallback on https_proxy for insecure connections

src/core/ext/filters/client_channel/http_proxy.cc

@@ -58,7 +58,6 @@ static char* get_http_proxy_server(char** user_cred,
     if (uri_str == nullptr) gpr_getenv("http_proxy");
   } else {
     uri_str = gpr_getenv("http_proxy");
-    if (uri_str == nullptr) gpr_getenv("https_proxy");
   }
   char* proxy_name = nullptr;
   char** authority_strs = nullptr;

tools/run_tests/generated/tests.json

@@ -22908,6 +22908,30 @@
       "posix"
     ]
   }, 
+  {
+    "args": [
+      "no_error_on_hotpath"
+    ], 
+    "ci_platforms": [
+      "windows", 
+      "linux", 
+      "posix"
+    ], 
+    "cpu_cost": 1.0, 
+    "exclude_configs": [], 
+    "exclude_iomgrs": [
+      "uv"
+    ], 
+    "flaky": false, 
+    "language": "c", 
+    "name": "h2_https_proxy_test", 
+    "platforms": [
+      "windows", 
+      "linux", 
+      "mac", 
+      "posix"
+    ]
+  }, 
   {
     "args": [
       "no_logging"