test: add explanation comment to oauth2 tests #1873

Job	Run time
setup	3s
test (./examples/with-i18next)	5m 25s
test (./examples/with-sign-in-up-split-emailpassword)	5m 10s
test (./examples/with-multiple-email-sign-in)	5m 32s
test (./examples/with-multifactorauth-recovery-codes)	5m 30s
test (./examples/with-multifactorauth-phone-chooser)	5m 30s
test (./examples/with-emailverification-with-otp)	5m 35s
test (./examples/with-update-email-post-verification)	6m 23s
test (./examples/with-thirdpartyemailpassword-passwordless)	5m 36s
test (./examples/with-phone-password)	6m 10s
test (./examples/with-legacy-2fa)	6m 53s
test (./examples/with-cli-login)	5m 12s
test (./examples/with-no-session-on-sign-up-thirdpartyemailpassword)	5m 10s
test (./examples/with-hash-router)	3m 45s
test (./examples/with-account-linking)	5m 9s
test (./examples/with-phone-password-mfa)	7m 14s
test (./examples/with-svelte-react-thirdpartyemailpassword)	5m 5s
test (./examples/with-localstorage)	3m 41s
test (./examples/with-one-login-per-subdomain)	5m 26s
test (./examples/with-netlify)	5m 38s
test (./examples/with-emailverification-then-password-thirdpartyemailpassword)	5m 34s
test (./examples/with-emailpassword-vercel)	5m 20s
	1h 55m 1s

Provide feedback