[cli][packages] unify the default dev server port to 8081 (#22880)

# Why

for historical reasons, when running `npx expo start` the dev-server listens to port 19000, and running `npx expo start --

[cli][packages] unify the default dev server port to 8081 (#22880)

# Why

for historical reasons, when running `npx expo start` the dev-server listens to port 19000, and running `npx expo start --dev-client` it listens to port 8081. since we are now on our effort to deprecate `--dev-client` option, it is better to unify the listening port.
close ENG-8936

# How

- update packages/**/*.ts for port 19000 -> 8081
- search more occurrences for 19000 to 8081

# Test Plan

- ci passed
- bare-expo
- unversioned expo go + ncl

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