Fix flaky Percy tests of ReplyChain (#10450)

* Fix flaky Percy tests of ReplyChain

- Add media query for percy on _ReplyChain.pcss to apply the same color to vertical strokes (border-left)of ReplyChain
- Use CSS variables for visibility
- Manage those variables on _common.pcss for maintainability

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

* Check receptSent as well for consistency

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

* Add a comment

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

* Specify zero spacing and remove list-style

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

---------

Signed-off-by: Suguru Hirahara <luixxiul@users.noreply.github.com>

res/css/_common.pcss

@@ -45,6 +45,14 @@ $timeline-image-border-radius: 8px;
     --MessageTimestamp-width: $MessageTimestamp_width;
 }
 
+@media only percy {
+    :root {
+        --percy-color-avatar: $username-variant2-color;
+        --percy-color-displayName: $username-variant1-color;
+        --percy-color-replyChain-border: $username-variant1-color;
+    }
+}
+
 @media (prefers-reduced-motion) {
     :root {
         --transition-short: 0;

res/css/views/avatars/_BaseAvatar.pcss

@@ -58,7 +58,7 @@ limitations under the License.
 @media only percy {
     /* Stick the default room avatar colour, so it doesn't cause a false diff on the screenshot */
     .mx_BaseAvatar_initial {
-        background-color: $username-variant2-color !important;
+        background-color: var(--percy-color-avatar) !important;
         border-radius: 125px;
     }
     .mx_RoomAvatar_isSpaceRoom .mx_BaseAvatar_initial {

res/css/views/elements/_ReplyChain.pcss

@@ -64,3 +64,11 @@ limitations under the License.
         --username-color: $username-variant8-color;
     }
 }
+
+/* Percy screenshot test specific CSS */
+@media only percy {
+    .mx_ReplyChain {
+        /* Override the colour in percy tests for screenshot consistency */
+        border-left-color: var(--percy-color-replyChain-border) !important;
+    }
+}

res/css/views/messages/_DisambiguatedProfile.pcss

@@ -38,6 +38,6 @@ limitations under the License.
 @media only percy {
     .mx_DisambiguatedProfile_displayName {
         /* Override the colour in percy tests for screenshot consistency */
-        color: $username-variant1-color !important;
+        color: var(--percy-color-displayName) !important;
     }
 }

res/css/views/rooms/_ReplyTile.pcss

@@ -139,3 +139,16 @@ limitations under the License.
         }
     }
 }
+
+@media only Percy {
+    /* Remove the list style in percy tests for screenshot consistency */
+    :is(ul, ol) {
+        padding: 0 !important;
+        margin: 0 !important;
+        list-style: none !important;
+
+        .mx_EventTile_last {
+            padding: 0 !important;
+        }
+    }
+}