fix #16818: override memcached options correctly

[tashik]

Hello!

• Type: bug fix
• Link to issue: [BUG]: Phalcon\Storage\Adapter\Libmemcached wrong client config Memcached options override #16818

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Small description of change:
Fixes merging numeric arrays keeping keys safe for \Memcached options constants

Thanks

Natalya

[niden]

@tashik Thank you. Good catch

[tashik]

@niden, OPT_CONNECT_TIMEOUT in Memcached is in milliseconds, I think to have the default 10 ms is not suitable for production with one memcached. Please, consider to set the default at least 50 ms