Rollup merge of #115503 - GuillaumeGomez:migrate-gui-test-color-38, r=notriddle

Migrate GUI colors test to original CSS color format

Follow-up of #111459.

r? `@notriddle`

Author: GuillaumeGomez

tests/rustdoc-gui/code-color.goml

@@ -19,6 +19,18 @@ define-function: (
     },
 )
 
-call-function: ("check-colors", ("ayu", "rgb(230, 225, 207)", "rgb(255, 180, 84)"))
-call-function: ("check-colors", ("dark", "rgb(221, 221, 221)", "rgb(221, 221, 221)"))
-call-function: ("check-colors", ("light", "rgb(0, 0, 0)", "rgb(0, 0, 0)"))
+call-function: ("check-colors", {
+    "theme": "ayu",
+    "doc_code_color": "#e6e1cf",
+    "doc_inline_code_color": "#ffb454",
+})
+call-function: ("check-colors", {
+    "theme": "dark",
+    "doc_code_color": "#ddd",
+    "doc_inline_code_color": "#ddd",
+})
+call-function: ("check-colors", {
+    "theme": "light",
+    "doc_code_color": "black",
+    "doc_inline_code_color": "black",
+})