test: ensure NODE_EXTRA_CA_CERTS not set before tests

The 'test-tls-env-extra-ca-file-load.js' test assumes that
NODE_EXTRA_CA_CERTS is not set. If the build environment
happens to have it set, this test will fail. This change
deletes that env var before running the test.

PR-URL: #43858
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

test/parallel/test-tls-env-extra-ca-file-load.js

@@ -20,6 +20,8 @@ if (process.argv[2] !== 'child') {
   const NODE_EXTRA_CA_CERTS = fixtures.path('keys', 'ca1-cert.pem');
   const extendsEnv = (obj) => ({ ...process.env, ...obj });
 
+  // Remove any pre-existing extra CA certs.
+  delete process.env.NODE_EXTRA_CA_CERTS;
   [
     extendsEnv({ CHILD_USE_EXTRA_CA_CERTS: 'yes', NODE_EXTRA_CA_CERTS }),
     extendsEnv({ CHILD_USE_EXTRA_CA_CERTS: 'no' }),