the separator has to be provided by the plugin

as generic env append/prepend can't handle path
separators, neither should it be handled here

src/vs/workbench/contrib/terminal/browser/media/fish_xdg_data/fish/vendor_conf.d/shellIntegration.fish

@@ -24,7 +24,7 @@ set --global VSCODE_SHELL_INTEGRATION 1
 
 # Apply any explicit path prefix (see #99878)
 if status --is-login; and set -q VSCODE_PATH_PREFIX
-	set -gx PATH "$VSCODE_PATH_PREFIX:$PATH"
+	set -gx PATH "$VSCODE_PATH_PREFIX$PATH"
 end
 set -e VSCODE_PATH_PREFIX
 

src/vs/workbench/contrib/terminal/browser/media/shellIntegration-bash.sh

@@ -34,7 +34,7 @@ if [ "$VSCODE_INJECTION" == "1" ]; then
 
 		# Apply any explicit path prefix (see #99878)
 		if [ -n "${VSCODE_PATH_PREFIX:-}" ]; then
-			export PATH="$VSCODE_PATH_PREFIX:$PATH"
+			export PATH="$VSCODE_PATH_PREFIX$PATH"
 			builtin unset VSCODE_PATH_PREFIX
 		fi
 	fi

src/vs/workbench/contrib/terminal/browser/media/shellIntegration-profile.zsh

@@ -12,7 +12,7 @@ if [[ $options[norcs] = off && -o "login" ]]; then
 
 	# Apply any explicit path prefix (see #99878)
 	if (( ${+VSCODE_PATH_PREFIX} )); then
-		export PATH="$VSCODE_PATH_PREFIX:$PATH"
+		export PATH="$VSCODE_PATH_PREFIX$PATH"
 	fi
 	builtin unset VSCODE_PATH_PREFIX
 fi