[x] stream: properties cleanup

• Streams are always initialized. Remove redundant checks.
• enumerable is false by default so there is no reason to explicitly set it.
• prefer method() {} over method: function() {}
• move properties directly after constructor

Refs: https://github.com/nodejs/node/issues/28967, https://github.com/nodejs/node/issues/28991

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines