set this.initialBackups as empty array as default and check for created backup after onboarding in storage tests (#327)

Author: sandyfzu

src/backwpup/features/storages/ftp.feature

@@ -16,6 +16,7 @@ Feature: Should be able to work with FTP storage
     Then I save and submit the onboarding form
     And I go '/wp-admin/admin.php?page=backwpup'
     Then I should see 'mixed' job cards
+    And '1' backup is generated and added to history
 
   Scenario: Setup FTP from Dashboard (After Onboarding)
     When I Configure web server storage

src/backwpup/features/storages/glacier.feature

@@ -16,6 +16,7 @@ Feature: Should be able to work with Amazon Glacier storage
     Then I save and submit the onboarding form
     And I go '/wp-admin/admin.php?page=backwpup'
     Then I should see 'mixed' job cards
+    And '1' backup is generated and added to history
 
   Scenario: Setup Amazon Glacier from Dashboard (After Onboarding)
     When I Configure web server storage

src/backwpup/features/storages/rsc.feature

@@ -16,6 +16,7 @@ Feature: Should be able to work with Rackspace storage
     Then I save and submit the onboarding form
     And I go '/wp-admin/admin.php?page=backwpup'
     Then I should see 'mixed' job cards
+    And '1' backup is generated and added to history
 
   Scenario: Setup Rackspace from Dashboard (After Onboarding)
     When I Configure web server storage

src/backwpup/features/storages/s3.feature

@@ -16,6 +16,7 @@ Feature: Should be able to work with S3 storage
     Then I save and submit the onboarding form
     And I go '/wp-admin/admin.php?page=backwpup'
     Then I should see 'mixed' job cards
+    And '1' backup is generated and added to history
 
   Scenario: Setup S3 from Dashboard (After Onboarding)
     When I Configure web server storage

src/backwpup/features/storages/sugarsync.feature

@@ -16,6 +16,7 @@ Feature: Should be able to work with SugarSync storage
     Then I save and submit the onboarding form
     And I go '/wp-admin/admin.php?page=backwpup'
     Then I should see 'mixed' job cards
+    And '1' backup is generated and added to history
 
   Scenario: Setup SugarSync from Dashboard (After Onboarding)
     When I Configure web server storage

src/backwpup/support/hooks.ts

@@ -20,7 +20,7 @@ Before({tags: '@bwpupsetup'}, async function(this: ICustomWorld, {pickle}) {
     this.sections = new Sections(this.page, pluginSelectors);
     this.utils = new PageUtils(this.page, this.sections);
     this.storage = new StorageUtils(this.page, this.sections);
-
+    this.initialBackups = [];
     this.pickle = pickle;
 });