introduce SKIP_BUNDLING_METRO_IP to skip ip.txt generation (#31829)

Summary:
ios debug archiving build will generate ip.txt that will leak metro server address for other people testing.
moreover, it will slow down launch time for metro server availability to wrong address.
this pr introduce `SKIP_BUNDLING_METRO_IP` to prevent ip.txt generation.

## Changelog

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[Internal] [iOS] [Changed] - introduce SKIP_BUNDLING_METRO_IP to skip ip.txt generation

Pull Request resolved: #31829

Test Plan:
### Classic build will generate ip.txt
```sh
xcodebuild -workspace RNTesterPods.xcworkspace -scheme RNTester -configuration Debug -sdk iphoneos -destination 'generic/platform=iOS'
find $HOME/Library/Developer/Xcode/DerivedData/RNTesterPods-* -name 'ip.txt'
```
this will find the ip.txt

### Specify `SKIP_BUNDLING_METRO_IP=1` will not generate ip.txt
```sh
SKIP_BUNDLING_METRO_IP=1 xcodebuild -workspace RNTesterPods.xcworkspace -scheme RNTester -configuration Debug -sdk iphoneos -destination 'generic/platform=iOS'
find $HOME/Library/Developer/Xcode/DerivedData/RNTesterPods-* -name 'ip.txt'
```
this will NOT find the ip.txt

Reviewed By: hramos

Differential Revision: D40095785

Pulled By: hramos

fbshipit-source-id: 0c913f078e683879e07e9ce3306e899d631206b2

scripts/react-native-xcode.sh

@@ -13,7 +13,7 @@ set -x
 DEST=$CONFIGURATION_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH
 
 # Enables iOS devices to get the IP address of the machine running Metro
-if [[ "$CONFIGURATION" = *Debug* && ! "$PLATFORM_NAME" == *simulator ]]; then
+if [[ ! "$SKIP_BUNDLING_METRO_IP" && "$CONFIGURATION" = *Debug* && ! "$PLATFORM_NAME" == *simulator ]]; then
   for num in 0 1 2 3 4 5 6 7 8; do
     IP=$(ipconfig getifaddr en${num})
     if [ ! -z "$IP" ]; then