Update reserved usernames list (#18438)

Adding additional usernames which are already routes, remove unused ones.
In future, avoid reserving names as much as possible, use `/-/` in path instead.

integrations/user_test.go

@@ -75,23 +75,41 @@ func TestRenameReservedUsername(t *testing.T) {
 	defer prepareTestEnv(t)()
 
 	reservedUsernames := []string{
+		".",
+		"..",
+		".well-known",
 		"admin",
 		"api",
+		"assets",
 		"attachments",
+		"avatar",
 		"avatars",
+		"captcha",
+		"commits",
+		"debug",
+		"error",
 		"explore",
-		"help",
-		"install",
+		"favicon.ico",
+		"ghost",
 		"issues",
 		"login",
+		"manifest.json",
 		"metrics",
+		"milestones",
+		"new",
 		"notifications",
 		"org",
 		"pulls",
+		"raw",
 		"repo",
-		"template",
-		"user",
+		"repo-avatars",
+		"robots.txt",
 		"search",
+		"serviceworker.js",
+		"ssh_info",
+		"swagger.v1.json",
+		"user",
+		"v2",
 	}
 
 	session := loginUser(t, "user2")

models/user/user.go

@@ -576,6 +576,7 @@ var (
 		"api",
 		"assets",
 		"attachments",
+		"avatar",
 		"avatars",
 		"captcha",
 		"commits",
@@ -584,10 +585,7 @@ var (
 		"explore",
 		"favicon.ico",
 		"ghost",
-		"help",
-		"install",
 		"issues",
-		"less",
 		"login",
 		"manifest.json",
 		"metrics",
@@ -595,15 +593,15 @@ var (
 		"new",
 		"notifications",
 		"org",
-		"plugins",
 		"pulls",
 		"raw",
 		"repo",
+		"repo-avatars",
 		"robots.txt",
 		"search",
 		"serviceworker.js",
-		"stars",
-		"template",
+		"ssh_info",
+		"swagger.v1.json",
 		"user",
 		"v2",
 	}