This is not currently possible. CodeMirror inherits the defaults of the textarea.
You could modify the code from:
wp_add_inline_script(
'code-editor',
sprintf( 'jQuery( function() { wp.codeEditor.initialize( "content", %s ); } );', wp_json_encode( $settings ) )
);
To
wp_add_inline_script(
'code-editor',
sprintf( 'jQuery( function() { var x = wp.codeEditor.initialize( "content", %s ); x.codemirror.setSize(null, 500); } );', wp_json_encode( $settings ) )
);
And replace 500 with the numbers of pixels you want as the height?
Patches welcome.