Build/Test Tools: Move composer update to env:start.

Currently, `composer update` is run whenever `test:php` is called to ensure the latest versions of `yoast/phpunit-polyfills` and other dependencies are always installed when running the PHPUnit test suite. 

For contributors using the local Docker environment to run tests during development, this is unnecessary and can often result in a 30+ second delay every time `test:php` is called.

This moves the command to `env:install`, reducing the number of times `composer update` is run from many to once. Since the environment needs to be started in order to run tests, `env:install` will still confirm that the latest versions of required dependencies are installed and available prior to running the test suite.

Props azaozz, swissspidy, johnbillion, peterwilsoncc, hellofromtonya.
Fixes #57189.

git-svn-id: https://develop.svn.wordpress.org/trunk@59231 602fd350-edb4-49c9-b593-d223f7449a82

package.json

@@ -179,7 +179,7 @@
 		"grunt": "grunt",
 		"lint:jsdoc": "wp-scripts lint-js",
 		"lint:jsdoc:fix": "wp-scripts lint-js --fix",
-		"env:start": "node ./tools/local-env/scripts/start.js",
+		"env:start": "node ./tools/local-env/scripts/start.js && node ./tools/local-env/scripts/docker.js run -T php composer update -W",
 		"env:stop": "node ./tools/local-env/scripts/docker.js down",
 		"env:restart": "npm run env:stop && npm run env:start",
 		"env:clean": "node ./tools/local-env/scripts/docker.js down -v --remove-orphans",
@@ -189,7 +189,7 @@
 		"env:logs": "node ./tools/local-env/scripts/docker.js logs",
 		"env:pull": "node ./tools/local-env/scripts/docker.js pull",
 		"test:performance": "wp-scripts test-playwright --config tests/performance/playwright.config.js",
-		"test:php": "node ./tools/local-env/scripts/docker.js run -T php composer update -W && node ./tools/local-env/scripts/docker.js run php ./vendor/bin/phpunit",
+		"test:php": "node ./tools/local-env/scripts/docker.js run php ./vendor/bin/phpunit",
 		"test:e2e": "wp-scripts test-playwright --config tests/e2e/playwright.config.js",
 		"test:visual": "wp-scripts test-playwright --config tests/visual-regression/playwright.config.js",
 		"sync-gutenberg-packages": "grunt sync-gutenberg-packages",