Stop creating services.yml by default

The question in #5 from @almaudoh was not answered. AFAICS It's not necessary to copy the complete default.services.yml to services.yml but it might be necessary to copy/set all options for a parameter and not just the one which should get overridden.

Example:

Set cookie_lifetime: 0 with following services.yml:

parameters:
  session.storage.options:
    cookie_lifetime: 0

After setting above code in services.yml and rebuilding cache the output of drush php:eval "var_export(\Drupal::getContainer()->getParameter('session.storage.options')) is:

array (
  'cookie_lifetime' => 0,
)

Which is different to the output with no services.yml which is:

array (
  'gc_probability' => 1,
  'gc_divisor' => 100,
  'gc_maxlifetime' => 200000,
  'cookie_lifetime' => 2000000,
  'cookie_samesite' => 'Lax',
  'sid_length' => 48,
  'sid_bits_per_character' => 6,
)

Therefore I assume that it might be necessary to define all options below for one parameter, at least if no defaults are defined by the corresponding service:

parameters:
  session.storage.options:
    gc_probability: 1
    gc_divisor: 100
    gc_maxlifetime: 200000
    cookie_lifetime: 0
    cookie_samesite: Lax
    sid_length: 48
    sid_bits_per_character: 6

Is that assumption right?

Anyway, looking at \Drupal\Core\Session\SessionConfiguration::__construct() shows that defaults are defined, so at least in this case the missing options shouldn't be problematic.