Rework user profile settings

Accessibility:

- improved semantic layout
- Fixes unlabelled input for custom pronouns. CC @hazy
- Adds labels to dropdowns.
- Shortens certain texts for less verbose screen reader outputs and
  people with slow reading speed.
- Turned optional username rename helper text with low contrast into
  "normal" help text.

UI/UX:

- Removes section about primary email which is no longer managed in the
  profile section.
- Fixes section about primary email not displaying in user settings when notifications are
  not available.
- Removes primary email display, because it is not actually a form
  element here. (Alternatively, we could display it and link to the
account settings for managing the email)

(cherry picked from commit 2885ea8da2)

tests/integration/setting_test.go

@@ -157,23 +157,3 @@ func TestSettingSecurityAuthSource(t *testing.T) {
 	assert.Contains(t, resp.Body.String(), `gitlab-active`)
 	assert.Contains(t, resp.Body.String(), `gitlab-inactive`)
 }
-
-func TestSettingShowUserEmailSettings(t *testing.T) {
-	defer tests.PrepareTestEnv(t)()
-
-	// user1: keep_email_private = false, user2: keep_email_private = true
-
-	// user1 can see own visible email
-	session := loginUser(t, "user1")
-	req := NewRequest(t, "GET", "/user/settings")
-	resp := session.MakeRequest(t, req, http.StatusOK)
-	htmlDoc := NewHTMLParser(t, resp.Body)
-	assert.Contains(t, htmlDoc.doc.Find("#signed-user-email").Text(), "user1@example.com")
-
-	// user2 cannot see own hidden email
-	session = loginUser(t, "user2")
-	req = NewRequest(t, "GET", "/user/settings")
-	resp = session.MakeRequest(t, req, http.StatusOK)
-	htmlDoc = NewHTMLParser(t, resp.Body)
-	assert.NotContains(t, htmlDoc.doc.Find("#signed-user-email").Text(), "user2@example.com")
-}