Fix various permission & login related bugs (#36002)

Permission & protection check:

- Fix Delete Release permission check
- Fix Update Pull Request with rebase branch protection check
- Fix Issue Dependency permission check
- Fix Delete Comment History ID check

Information leaking:

- Show unified message for non-existing user and invalid password
    - Fix #35984
- Don't expose release draft to non-writer users.
- Make API returns signature's email address instead of the user
profile's.

Auth & Login:

- Avoid GCM OAuth2 attempt when OAuth2 is disabled
    - Fix #35510

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/integration/api_repo_test.go

@@ -41,17 +41,6 @@ func TestAPIUserReposNotLogin(t *testing.T) {
 	}
 }
 
-func TestAPIUserReposWithWrongToken(t *testing.T) {
-	defer tests.PrepareTestEnv(t)()
-	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
-	wrongToken := "Bearer " + "wrong_token"
-	req := NewRequestf(t, "GET", "/api/v1/users/%s/repos", user.Name).
-		AddTokenAuth(wrongToken)
-	resp := MakeRequest(t, req, http.StatusUnauthorized)
-
-	assert.Contains(t, resp.Body.String(), "user does not exist")
-}
-
 func TestAPISearchRepo(t *testing.T) {
 	defer tests.PrepareTestEnv(t)()
 	const keyword = "test"