Remove manually added css variable

Author: tuan-nguen

extensions/ql-vscode/src/stories/vscode-theme-dark.css

@@ -18,7 +18,6 @@
   --vscode-descriptionForeground: rgba(204, 204, 204, 0.7);
   --vscode-icon-foreground: #c5c5c5;
   --vscode-focusBorder: #007fd4;
-  --vscode-contrastActiveBorder: #f38518;
   --vscode-textSeparator-foreground: rgba(255, 255, 255, 0.18);
   --vscode-textLink-foreground: #3794ff;
   --vscode-textLink-activeForeground: #3794ff;

extensions/ql-vscode/src/stories/vscode-theme-github-dark-default.css

@@ -19,7 +19,6 @@
   --vscode-descriptionForeground: #8b949e;
   --vscode-icon-foreground: #8b949e;
   --vscode-focusBorder: #1f6feb;
-  --vscode-contrastActiveBorder: #f38518;
   --vscode-textSeparator-foreground: #21262d;
   --vscode-textLink-foreground: #58a6ff;
   --vscode-textLink-activeForeground: #58a6ff;

extensions/ql-vscode/src/stories/vscode-theme-github-light-default.css

@@ -19,7 +19,6 @@
   --vscode-descriptionForeground: #57606a;
   --vscode-icon-foreground: #57606a;
   --vscode-focusBorder: #0969da;
-  --vscode-contrastActiveBorder: #f38518;
   --vscode-textSeparator-foreground: #d8dee4;
   --vscode-textLink-foreground: #0969da;
   --vscode-textLink-activeForeground: #0969da;

extensions/ql-vscode/src/stories/vscode-theme-light.css

@@ -18,7 +18,6 @@
   --vscode-descriptionForeground: #717171;
   --vscode-icon-foreground: #424242;
   --vscode-focusBorder: #0090f1;
-  --vscode-contrastActiveBorder: #0f4a85;
   --vscode-textSeparator-foreground: rgba(0, 0, 0, 0.18);
   --vscode-textLink-foreground: #006ab1;
   --vscode-textLink-activeForeground: #006ab1;