chore: relax npm version constraint in installation tests

.github/workflows/tests_primary.yml

@@ -176,7 +176,7 @@ jobs:
     - uses: actions/setup-node@v2
       with:
         node-version: ${{ matrix.node_version }}
-    - run: npm i -g npm@8.15.1 # This should NOT be pinned beyond major version once https://github.com./microsoft/playwright/issues/16281 is resolved.
+    - run: npm i -g npm@8
     - run: npm ci
       env:
         DEBUG: pw:install

.github/workflows/tests_secondary.yml

@@ -128,7 +128,7 @@ jobs:
     - uses: actions/setup-node@v2
       with:
         node-version: ${{ matrix.node_version }}
-    - run: npm i -g npm@8.15.1 # This should NOT be pinned beyond major version once https://github.com./microsoft/playwright/issues/16281 is resolved.
+    - run: npm i -g npm@8
     - run: npm ci
       env:
         DEBUG: pw:install

tests/installation/npx-global-help.spec.ts

@@ -16,7 +16,7 @@
 import { test, expect } from './npmTest';
 
 test('npx playwright --help should not download browsers', async ({ exec, installedSoftwareOnDisk }) => {
-  const result = await exec('npx playwright --help');
+  const result = await exec('npx playwright --help', { env: { npm_config_prefix: '' } }); // global npx and npm_config_prefix do not work together nicely (https://github.com./npm/cli/issues/5268)
   expect(result).toHaveLoggedSoftwareDownload([]);
   expect(await installedSoftwareOnDisk()).toEqual([]);
   expect(result).not.toContain(`To avoid unexpected behavior, please install your dependencies first`);

tests/installation/npx-global-install.spec.ts

@@ -17,7 +17,7 @@ import { test, expect } from './npmTest';
 
 test('npx playwright install global', async ({ exec, installedSoftwareOnDisk }) => {
   test.skip(process.platform === 'win32', 'isLikelyNpxGlobal() does not work in this setup on our bots');
-  const result = await exec('npx playwright install');
+  const result = await exec('npx playwright install', { env: { npm_config_prefix: '' } }); // global npx and npm_config_prefix do not work together nicely (https://github.com./npm/cli/issues/5268)
   expect(result).toHaveLoggedSoftwareDownload(['chromium', 'ffmpeg', 'firefox', 'webkit']);
   expect(await installedSoftwareOnDisk()).toEqual(['chromium', 'ffmpeg', 'firefox', 'webkit']);
   expect(result).not.toContain(`Please run the following command to download new browsers`);

tests/installation/npx-global-spec-codegen.spec.ts

@@ -16,7 +16,7 @@
 import { test, expect } from './npmTest';
 
 test('npx playwright codegen', async ({ exec, installedSoftwareOnDisk }) => {
-  const stdio = await exec('npx playwright codegen', { expectToExitWithError: true });
+  const stdio = await exec('npx playwright codegen', { expectToExitWithError: true, env: { npm_config_prefix: '' } }); // global npx and npm_config_prefix do not work together nicely (https://github.com./npm/cli/issues/5268)
   expect(stdio).toHaveLoggedSoftwareDownload([]);
   expect(await installedSoftwareOnDisk()).toEqual([]);
   expect(stdio).toContain(`Please run the following command to download new browsers`);