refactor: remove unused observable and functions from general-store

[nada-deriv]

Changes:

This PR is for removing the unused observables and functions in general-store.

Screenshots:

Please provide some screenshots of the change.

[vercel]

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Name	Status	Preview	Updated (UTC)
deriv-app	✅ Ready (Inspect)	Visit Preview	Nov 23, 2023 7:51am

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
11.6% Duplication

[coveralls]

coverage: 28.191% (+0.006%) from 28.185%
when pulling a73331c on nada-deriv:nada/P2PS-1928/general-store-remove-unused
into 532d47b on binary-com:master.

[github-actions]

A production App ID was automatically generated for this PR. (log)

• PR: refactor: remove unused observable and functions from general-store #11703
• URLs:
  • w/ App ID + Server: https://deriv-app-git-fork-nada-deriv-nada-p2ps-1928general-stor-e3b4cf.binary.sx?qa_server=red.derivws.com&app_id=32126
  • Original: https://deriv-app-git-fork-nada-deriv-nada-p2ps-1928general-stor-e3b4cf.binary.sx
• App ID: 32126

Click here to copy & paste above information.

- **PR**: [https://github.com/binary-com/deriv-app/pull/11703](https://github.com/binary-com/deriv-app/pull/11703)
- **URLs**:
    - **w/ App ID + Server**: https://deriv-app-git-fork-nada-deriv-nada-p2ps-1928general-stor-e3b4cf.binary.sx?qa_server=red.derivws.com&app_id=32126
    - **Original**: https://deriv-app-git-fork-nada-deriv-nada-p2ps-1928general-stor-e3b4cf.binary.sx
- **App ID**: `32126`

[github-actions]

🚨 Lighthouse report for the changes in this PR:

Category	Score
🔺 Performance	16
🟧 Accessibility	75
🟢 Best practices	92
🟧 SEO	85
🟧 PWA	80

Lighthouse ran with https://deriv-app-git-fork-nada-deriv-nada-p2ps-1928general-stor-e3b4cf.binary.sx/

[github-actions]

🚀 Smoke test run (1) passed successfully!

[markw-deriv]

Love removing stuff from these stores 😍