e2e tests: Consolidate tunnel manager scripts

[adimoldovan]

Proposed changes:

Refactored tunnel management scripts by consolidating Cloudflare and LocalTunnel logic into a unified TunnelManager structure.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

n/a

Does this pull request change what data or activity we track or use?

no

Testing instructions:

• e2e tests pass in CI

Locally, run both tunnel options and ensure they work:

pnpm tunnel:up
pnpm tunnel:down
pnpm tunnel:reset


USE_CLOUDFLARE_TUNNEL=1 pnpm tunnel:up
USE_CLOUDFLARE_TUNNEL=1 pnpm tunnel:down
USE_CLOUDFLARE_TUNNEL=1 pnpm tunnel:reset

[github-actions]

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