fix sidebar and links as they have been broken on the master branch

Error:  Error: Unable to build website for locale en.
[cause]: Error: Invalid sidebar file at "sidebars.js".
These sidebar document ids do not exist:
  - testfairy/ci-tools/bamboo
  - testfairy/ci-tools/ms-app-ctr
  - testfairy/integrations/centercode
  - testfairy/integrations/coralogix
  - testfairy/integrations/google-cloud
  - testfairy/integrations/splunk
  - testfairy/integrations/zendesk

- Broken link on source page path = /pr-preview/pr-3093/testfairy/security/acct-settings/:
   -> linking to /pr-preview/pr-3093/testfairy/integrations/zendesk/

Author: przemek-sl

docs/testfairy/security/acct-settings.md

@@ -44,8 +44,6 @@ You can integrate your TestFairy account with different services to customize an
 
 - Slack - See [Slack](/testfairy/integrations/slack) for information about integrating your Slack account with TestFairy.
 
-- Zendesk - See [ZenDesk](/testfairy/integrations/zendesk) for information about integrating your Zendesk account with TestFairy.
-
 - Webhooks - You can use TestFairy webhooks to connect to services. See [Microsoft Teams](/testfairy/integrations/ms-teams) for more information.
 
 <img src={useBaseUrl('img/testfairy/acct-settings-integrations.png')} alt="Integrations page" width="700"/>

sidebars.js

@@ -1211,14 +1211,9 @@ module.exports = {
                     label: 'Integrations',
                     collapsed: true,
                     items: [
-                        'testfairy/integrations/centercode',
-                        'testfairy/integrations/coralogix',
                         'testfairy/integrations/slack',
                         'testfairy/integrations/smtp-gmail',
-                        'testfairy/integrations/splunk',
-                        'testfairy/integrations/zendesk',
                         'testfairy/integrations/ms-teams',
-                        'testfairy/integrations/google-cloud',
                         'testfairy/integrations/apple-uploading',
                         'testfairy/integrations/google-uploading',
                     ],
@@ -1228,12 +1223,10 @@ module.exports = {
                     label: 'CI Tools',
                     collapsed: true,
                     items: [
-                        'testfairy/ci-tools/bamboo',
                         'testfairy/ci-tools/bitbucket',
                         'testfairy/ci-tools/circle-ci',
                         'testfairy/ci-tools/fastlane',
                         'testfairy/ci-tools/gitlab',
-                        'testfairy/ci-tools/ms-app-ctr',
                         'testfairy/ci-tools/team-city',
                         'testfairy/ci-tools/vs-team',
                     ],