MDL-77577 Behat: Replaced the use of "Install selected language pack(s)

Evaluated usage of "Install selected language pack(s)" in Behat and
replaced the steps to use generator to install language packs as part
of test setup.

auth/tests/behat/loginform.feature

@@ -18,17 +18,16 @@ Feature: Test if the login form provides the correct feedback
 
   Scenario: Test login language selector
     Given remote langimport tests are enabled
-    And I log in as "admin"
-    And I navigate to "Language > Language packs" in site administration
-    And I set the field "Available language packs" to "nl,es"
-    And I press "Install selected language pack(s)"
-    And I trigger cron
-    And I am on homepage
-    And I log out
+    And the following "language packs" exist:
+      | language |
+      | nl       |
+      | es       |
+    And the following config values are set as admin:
+      | langmenu | 1 |
     And I follow "Log in"
     And I open the action menu in "region-main" "region"
     # The line below contains the unicode character U+200E before and after the brackets, please be very careful editing this line.
-    And I choose "Nederlands ‎(nl)‎" in the open action menu
+    When I choose "Nederlands ‎(nl)‎" in the open action menu
     Then I should see "Gebruikersnaam"
 
   @_file_upload

calendar/tests/behat/calendar_utf8.feature

@@ -8,11 +8,9 @@ Feature: Verify that the day and month names are displayed using UTF-8
     Given remote langimport tests are enabled
 
   Scenario Outline: View the calendar for December 2012 with correct UTF-8
-    Given I log in as "admin"
-    And I navigate to "Language > Language packs" in site administration
-    And I set the field "Available language packs" to "<lang>"
-    And I press "Install selected language pack(s)"
-    And I should see "Language pack '<lang>' was successfully installed"
+    Given the following "language pack" exists:
+      | language | <lang> |
+    And I log in as "admin"
     And I follow "Preferences" in the user menu
     And I follow "Preferred language"
     And I set the field "Preferred language" to "<lang>"

theme/boost/tests/behat/languagemenu.feature

@@ -15,12 +15,8 @@ Feature: Language selector menu
     And the following "course enrolments" exist:
       | user | course | role |
       | teacher1 | C1 | editingteacher |
-    And I log in as "admin"
-    And I navigate to "Language > Language packs" in site administration
-    And I set the field "Available language packs" to "en_ar"
-    And I press "Install selected language pack(s)"
-    And the "Installed language packs" select box should contain "en_ar"
-    And I log out
+    And the following "language pack" exists:
+      | language | en_ar |
 
   Scenario: Logged user is presented with a language selector which is placed within the user menu
     Given I log in as "teacher1"