[KoushikSagarr]

What github issue is this PR for, if any?

Resolves [#7325]

What changed, and why?

• Deleted the obsolete bin/bundle Bundler binstub.
• Confirmed that no project scripts, CI workflows, or Dockerfiles invoke bin/bundle.
• Verified that the existing bin/setup, bin/update, and bin/dev scripts use the system bundle executable from PATH.
• Kept changes strictly limited to removing the obsolete binstub.

This is another small, independently reviewable contribution toward simplifying CASA's development and deployment setup.

How is this tested? (please write rspec and jest tests!) 💖💪

• Bundler: bundle check passed; all dependencies are satisfied.
• Asset build: npm run build && npm run build:css completed successfully.
• RSpec: Smoke test — 1 example, 0 failures.
• Reference verification: Confirmed no remaining project references to bin/bundle.
• Git diff: git diff --check passed with no whitespace errors.

Screenshots please :)

Not applicable — this PR removes a command-line binstub without introducing UI changes.

Feelings gif (optional)

One less obsolete file, one cleaner deployment setup. Keeping CASA tidy! 💪