(dev/cloud-native#3) SerializeCache - Remove unused, incomplete cache-driver

[totten]

Overview

The class CRM_Utils_Cache_SerializeCache provides a cache-driver for
storing cache records in the filesystem (under CIVICRM_TEMPLATE_COMPILEDIR,
using PHP serialize() format). Why remove it?

1. As we work through cleanup in file management (e.g. Lookup path-variable for the private filepath #12843,
   dev/cloud-native#3), having an unnecessary reference to
   CIVICRM_TEMPLATE_COMPILEDIR makes it harder to reason about the system.

2. The class is not used. I'm pretty sure it was added speculatively
   (i.e. with an aim to try using it some day), but that never came to
   pass. Grepping universe, I cannot find any usages or references to
   SerializeCache.

3. The implementation is incomplete -- parameters like get(..., $default)
   and set(..., $ttl) will generate exceptions if used.

Before

• Driver exists and is not used.

After

• Driver does not exist.

[civibot]

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[eileenmcnaughton]

@totten test failure looks like server needs a kick

[eileenmcnaughton]

I agree with your analysis - I did a couple of further checks

1. checked that no functional commits had taken place on the file since it was brought over from svn (it did get some changes as part of various cleanups & stdisations but none that suggest it was targetted)
2. searched for a 'Serialize' (case sensitive) in case it was being concatenated in the core code base
3. checked the references to cache options in civicrm.settings.template.php

I feel comfortable this can be removed & we can stop 'fixing it' to meet standards

[totten]

jenkins, test this please

[eileenmcnaughton]

test this please