fxa-12621: Migrate 14 Mocha integration tests to Jest

[vbudhram]

Because

• Auth server integration tests were split across Mocha and Jest, making CI slower and harder to maintain
• The Mocha test runner lacks Jest's parallel execution, better error reporting, and modern async handling

This pull request

• Migrates 14 Mocha integration test files to Jest .in.spec.ts format in test/remote/
• Adds shared test infrastructure: test-process-registry.ts for server lifecycle management, test-utils.ts for common helpers
• Updates jest-global-setup.ts and jest-global-teardown.ts to boot/teardown the auth server for integration tests
• Updates test-server.ts with OAuth config overrides to fix assertion verification mismatches
• Updates test-ci.sh to skip mocha tests when TEST_TYPE=integration-jest, running only Jest suites
• Changes test-integration-jest npm script to route through test-ci.sh for consistency
• Sets maxWorkers: 4 in jest.integration.config.js

Mocha → Jest test parity

File	Mocha	Jest	Status
account_create	39	39	Full parity
account_create_with_code	7	7	Full parity
account_destroy	7	7	Full parity
account_locale	2	2	Full parity
account_login	13	13	Full parity
account_profile	12	12	Full parity
account_reset	5	5	Full parity
account_signin_verification	8	8	Full parity
account_status	9	9	Full parity
account_unlock	3	3	Full parity
base_path	4	2 + 2 todo	Intentional skip
concurrent	1	1	Full parity
db	23	23	Full parity
email_validity	2	2	Full parity
flow	2	2	Full parity

base_path: 2 tests marked todo — they test __lbheartbeat__ and __version__ endpoints not present in the spawned
key_server.

Issue

Closes: https://mozilla-hub.atlassian.net/browse/FXA-12621

Checklist

• My commit is GPG signed
• Tests pass locally
• Documentation updated (if applicable)
• RTL rendering verified (if UI changed)

Other Information

Notable behavior change: The Mocha test "cannot stub the same account twice" had an un-awaited assert.isRejected() that was effectively a no-op. The Jest version correctly tests actual server behavior as "can re-stub an unverified account".