DEVXT-1781: Upgrade backstage backend

[MonicaG]

• update to version 1.32.4
• updated to use new backend system

Major changes:

• Removed all of the packages/backend/src/plugins files
  • The catalog and stackoverflow configuration that were done in the catalog.ts and search.ts files were moved into the app-config.production.yaml file
  • Permission code was moved into new packages/backend/src/extensions/permissionsPolicyExtension.ts file
  • I also tried to clean up the spread of configuration. The stackoverflow and auth configs are now part or app-config.production.yaml file instead of having to be defined in every values.*.yaml file in the gitops repo.
• Added the ProxiedSignInPage to the packages/app/src/App.tsx file.
  • This will allow us to use the site as before
  • updated the auth configuration in app-config.production.yaml to allow this process
• Removed the LEGACY_BACKEND_START from the Dockerfile as we are now using the new backend
  • Also updated the Dockerfile to not pin the image tag. This will let us get security updates if available on a new build and is Docker's recommendation

Notes:

• There is some whitespace formatting changes with the checkin because of our husky processor. These formatting changes will start to settle down as we update files.
• Backstage has updated to yarn 4. I have created a separate ticket for that, as this PR is large enough.

[sheaphillips]

Taking a look at this now...

[sheaphillips]

I've looked through the changes and also brought this up locally. I don't have any concerns, other than maybe capturing a sample app config sometwhere for us to use internally, and maybe updating the README?

[oomIRL]

Looks good!

[MonicaG]

I've looked through the changes and also brought this up locally. I don't have any concerns, other than maybe capturing a sample app config sometwhere for us to use internally, and maybe updating the README?

I've updated the README file and provided an app-config.local.template.yaml file