Resolve "Move add-on related data to GraphQL"

What does this MR do and why?

[This is the last part of moving addon related data into GraphQL and related refactor and resolves this issue]

This MR:

• Moves planCode constant from constants to the only file which uses it for simplicity
• Injects tags to buy_addons_shared instead of passing it as a prop from a parent component
• Groups addon related translations together in respective constants which is then injected to the app component from minutes app and storage app
• Removes redundant components buy_storage and buy_minutes and their tests that are no longer used as a result of the above changes

Tests were written before this refactor to makes sure these changes don't break anything.

Screenshots or screen recordings

The UI is unchanged and is exactly the same as before.

Addon	Before	After
CI Minutes
Storage

How to set up and validate locally

1. Go to Usage Quotas for a group that you own
2. Go to Storage tab and click on Purchase more storage

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Closes #346620 (closed)